ST STFPC311 User Manual

Features

■ IC front panel controller/driver

■ Timing power standby management controller

■ IC power supply from 3.3V (V

■ Integrated VFD driver and controller

■ Infrared (IR) Remote Control (RC) Decoder

(Philips or NEC format)

■ Drives many display modes (12 segments/16

digits to 20 segments/8 digits)

■ High voltage outputs (V

■ No external resistors necessary for driver

DD

outputs (P-channel open- drain with pull-down resistor outputs)

■ Key scanning (up to 12mm x 2mm matrix)

■ Led ports (4 channels, 20mA, max)

■ Serial interface (STB, CLK, D

communication protocol

■ Dimming circuit (adjustable up to 8 steps)

■ Supports auto-increment of display digit, which

lightens the load on the MCU

■ Programmable 8 hot keys for the IR remote

control command

■ Programmable 8 hot keys for key scan

command

■ Low power consumption in standby mode

■ 2 general purpose input ports (SW1, SW2)

■ Available in PQFP-52 package

) to –30V (VSS)

DD

- 33.3V max)

, and D

IN

OUT

)

STFPC311

Front panel controller/driver

with standby power management

PQFP-52

Description

The STFPC311 is a complete, low-cost, integrated solution for controlling and driving a front panel Vacuum Fluorescent Display (VFD). It is ideal for decreasing power consumption in standby mode by reducing the application standby current to a minimum. It also contains a built-in remote control decoder module.

While in the standby mode of operation, a valid key press or signal from infrared decoder will start a proper power-up see Figure 6 on page 12.

The STFPC311 integrates a VFD controller with a driver that is run on a 1/8 to 1/16-duty factor. It consists of 12 segments output lines, 8 grid output lines, 8 shared segments/grid output drive lines, a display memory, a control circuit, and a key scan circuit. Serial data is input to the STFPC311 through the SPI Interface of a microcontroller (STB, D

Additionally, this IC can support 2 general purpose input switches (SW1 and SW2).

Features

, D

IN

, and CLK).

OUT

■ DVD players

■ VCD players

■ AV equipment like Home Stereo

■ POS Systems

Order Codes

Part number Temperature range Package

STFPC311 -40 to 85°C PQFP-52

May 2006 Rev 1 1/39

www.st.com

39

STFPC311

Contents

1 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.1 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.1 Normal mode of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.2 Receive operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.3 Transmit operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.4 Standby or power-down mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.5 IR Decoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.6 Watchdog timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.6.1 Watchdog timer operation during power-up . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.6.2 Watchdog timer operation during power-down . . . . . . . . . . . . . . . . . . . . . . . 10

3.6.3 Watchdog timer operation during standby . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.7 Flow charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

4 Display RAM address and display mode . . . . . . . . . . . . . . . . . . . . . . . . . . 15

5 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.1 LED Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.2 SW Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

6 Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

6.1 Configuration mode setting command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

6.2 Data setting command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

6.3 Address setting command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

6.4 Display control and hotkey setting command . . . . . . . . . . . . . . . . . . . . . . . . 20

7 Programmable hotkeys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

7.1 IR Remote control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

7.2 Front panel keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2/39

STFPC311

8 Default status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

8.1 Power-up default status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

8.2 STANDBY status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

9 Remote control protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

9.1 RC-5 remote control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

9.2 SPI interface IR data transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

9.3 NEC remote control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

10 Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

10.1 Power consumption estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

11 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

12 Timing characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

13 Serial communication format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

14 Typical application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

15 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

16 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

3/39

1 Functional description STFPC311

1 Functional description

The STFPC311 receives serial data from the microcontroller through the SPI interface, latches the data, and then masks the inputs from the MCU. This data consists of commands followed by data. There are 4 types of commands:

● configuration,

● data,

● address, and

● display.

The STFPC311 integrates the supply standby power management functionality, remote control decoder, and a 28-bit VFD driver. Microcontrollers usually run the first two tasks.

This device reduces the stand-by power consumption of the whole Front Panel application as well as the hardware by integrating the infrared (IR) remote control decoder.

A dedicated supply voltage powers the STFPC311 directly from the main supply board. When power is plugged in, control of the power supply management is done using the following pins:

1. STBY,

2. IR_DATA_IN, and

3. READY.

1.1 Block diagram

Figure 1. Block diagram

IR_ DATA_ IN

READY/STBY_n

D

IN

D

OUT

CLK

CLK STB

STB

V

DD

R

OSC

SW1

SW2

KEY1

KEY1 KEY2

KEY2

2

Seri al

OSC

2-bit

Lat ch

SPI

I/F

Remote Control

Decoder & Stand

By Function

Command Decod er

Display Memory

(20 x 16)

Timing Generator

Key Scan and

Dimmi ng Circuit

Key Dat a Memor y

(2 x 12)

2

Lat ch

4-bit

LED1

LED2

LED3

LED4

STBY

MUTE

20-bit

Out put

Lat ch

16-bit

Shift

Regis ter

V

DD

(+3.3V)

GND

(0V)

Watchdog

Timer

20 12

8

Dat a

Selec tor

8

16

V

SS

(-30V)

SEG1/KS1

Dri vers

Segment

8

Multiplexed

Gri d

8

Dri vers

SEG12/KS2

SEG13/GRID16

SEG20/GRID9

GRID8

GRID1

4/39

STFPC311 2 Pin connection

2 Pin connection

Figure 2. Connection diagram (top view PQFP-52)

STFPC311

Note: For a description of the behavior of each pin, refer to the Table 1: Pin description on page 6.

5/39

2 Pin connection STFPC311

2.1 Pin description

Table 1. Pin description

Pin Nº Symbol Type Name and function

1 OSC I This is the oscillator input pin. Connect this pin to an external resistor.

2, 3 SW1, SW2 I General purpose switch input ports.

4MUTEO

5S TBY O

7 GND POWER Connect this pin to system GND.

High level indicates mute status for audio. Low level indicates normal working.Note 1

there is a typo. Pin5 and name is STBY. Standby output to put the MCU in low power mode.

It is a command to the main power board. High level indicates stand-by status. Low level indicates normal working. Note 1

8, 9 KEY1, KEY2 I

Input data to these pins from external keyboard are latched at end of the display cycle (maximum keyboard size is 12 x 2).

High level on this pin means that main board chip has been working

10 READY I

normally.Note 1 This pin should never float. It is recommended have a pull-down resistor on this input.

1 IR_DATA_IN I Remote control input. Feeds the IR data from photodiode to this pin.

14 to 25

12, 26

27 to 34

SEG1/KS1 to SEG12/KS12

V

SS

SEG13/GRID16

to SEG20/GRID9

O Segment output pins (dual function as key source).

V

POWER

outputs high voltage pull-down level. VDD--33.3V max.

FD

O These pins are selectable for segment or grid driving.

35 to 37 GRID8 to GRID6 O Grid output pins.

6, 13,38

V

DD

POWER 3.3V ± 0.3V Core main supply voltage.

39 NC O Not used. Left unconnected.

40 to 44 GRID5 to GRID1 O Grid output pins.

Initializes the serial interface at the rising or falling edge to make the STFPC31 wait for reception of command. The data input after the falling

45 STB I

edge of STB is processed as a command. While the command data is processed, current processing is stopped, and the serial interface is initialized. While STB is high, CLK is ignored and any instruction from

the MCU is neglected.

46 CLK I

Reads serial data at the rising edge, and outputs data at the falling edge.

47

48

49-52

D

IN

D

OUT

LED1, LED2,

LED3, LED4

O

O CMOS outputs (20mA, max).

Inputs serial data at the rising edge of the shift clock, starting from the

I

lower bit.

Outputs serial data at the faling edge of the shift clock, starting from the lower bit. This is the N-channel opendrain output pin.

Note: 1 For a detailed behavioral description of these pins, refer to the “STFPC311 Timing Power

Stand-by Sequencer Flow-Chart”. See Table 6 on page 12

6/39

STFPC311 3 Initialization

3 Initialization

After the power is plugged in, the device will supply power to all of the components (including the host processor) by setting STBY to logic low in order to allow the host processor to program the STFPC311. Once the STBY is set to low, the watchdog timer starts to count up to 10s (10s is the default value of the watchdog timer upon power-up). When the READY is asserted within this time, it indicates that the system has booted up well. If the READY pin is not asserted (logic high) within this time (10s), the STFPC311 will put the system into standby mode again by setting STBY to logic high.

If READY is detected as logic high, the watchdog timer will be turned OFF. The main processor should program the remote control hot key and initialize the other parameters of the STFPC311 in preparation for normal operation before the system goes into standby mode. After all of the STFPC311 configuration is finished, the host processor may set the READY to low so that the STFPC311 enters standby mode. The STFPC311 then sets the MUTE pin to logic high to mute the audio output as well as the STBY pin to logic high. As a consequence of this action, the main supply voltage is turned off.

3.1 Normal mode of operation

After the power is plugged in, the device will supply power to all of the components (including the host processor) by setting STBY to logic low in order to allow the host processor to program the STFPC311. Once the STBY is set to low, the watchdog timer starts to count up to 10s (10s is the default value of the watchdog timer upon power-up). When the READY is asserted within this time, it indicates that the system has booted up well. If the READY pin is not asserted (logic high) within this time (10s), the STFPC311 will put the system into standby mode again by setting STBY to logic high.

If READY is detected as logic high, the watchdog timer will be turned OFF. The main processor should program the remote control hot key and initialize the other parameters of the STFPC311 in preparation for normal operation before the system goes into standby mode. After all of the STFPC311 configuration is finished, the host processor may set the READY to low so that the STFPC311 enters standby mode. The STFPC311 then sets the MUTE pin to logic high to mute the audio output as well as the STBY pin to logic high. As a consequence of this action, the main supply voltage is turned off.

3.2 Receive operation

In receive condition, the STFPC311 waits for a valid command from the MCU. The receive circuit of STFPC311 receives 8 bit serial data, latches the data and then masks the inputs from the MCU. Refer to Figure 28 on page 32 for receive timing.

3.3 Transmit operation

In transmit condition, the STFPC311 sends the 8-bit serial data (LSB transmitted first) whenever a key is pressed or IR data is received. STFPC311 transmits data on the falling edge of CLK. Refer to Figure 29 on page 32 for transmit timing.

7/39

3 Initialization STFPC311

3.4 Standby or power-down mode

Once the STFPC311 detects the status change of the READY to a logic low or after the preset waiting time (1s to 15s) has elapsed, the STFPC311 sets the STBY pin to a logic high to turn off the power. The MUTE signal is set to high before the power is turned off. The STFPC311 always senses the level on the READY pin during normal operation.

3.5 IR Decoding

Encoded IR data from photodiode is supplied to the IR_DATA_IN input pin. The data is decoded by the internal remote control decoder module of STFPC311. In standby mode, the remote control decoder recognizes a set of predefined commands (such as STANDBY, PLAY, and OPEN/CLOSE), and takes appropriate action to manage the power supply.

These predefined commands are known as "hot keys" and are programmable. The decoded IR commands are passed on to the main processor through the SPI interface by sending 3 bytes of data on the D

OUT

pin.

3.6 Watchdog timer

The watchdog timer is used to detect an out-of-control microprocessor. The watch dog timer is implemented in the STFPC311 to detect the abnormal processor behavior or processor-hung condition. The default state of the watchdog timer is 10s when the device powers-up. It is initialized by writing to the watchdog register and can be programmed to up to 15s (4-bit watchdog timer, present in the configuration mode setting command).

If the processor does not reset the timer within the specified period, the STFPC311 will put the entire system into standby mode to reset the appliance that has stopped abnormally. The action to take when the watchdog timer has reached its count is to set the Watchdog Action register. The watchdog timer can be reset by the host processor by sending a command to reset the watchdog timer. The time-out period then starts over again. If the processor needs to be reset as a result of a hung condition (signalled using the STBY output of the STFPC311), the watchdog timer uses the amount of the time-out programmed into the Watchdog Register by the user to generate an interrupt.

Note: The accuracy of the timer is within ±10% the selected resolution. This depends on the value of

the external bias resistor, as it determines the internal clock frequency.

The watchdog function is automatically set to 10s upon power-up and the Watchdog Interrupt is cleared. This boot-up watchdog timer is used to make sure that if the host processor hangs during the first boot-up, the STFPC311 will put the system to standby mode. During the first boot-up, the watchdog timer is disabled after the first READY signal is received.

8/39

STFPC311 3 Initialization

3.6.1 Watchdog timer operation during power-up

Figure 3. Power-up condition

Note: Watchdog timer is turned off by default upon READY assertion.

If Watchdog is to be kept on during READY high condition, the WDG registers must be set accordingly by proper commands through SPI bus.

In this power-up condition, the watchdog timer is triggered by internal POR pulse.

During power-up, the watchdog timer value is 10s.

9/39

3 Initialization STFPC311

3.6.2 Watchdog timer operation during power-down

Figure 4. Power-down condition

Note: The watchdog timer can be kept on during normal conditions when READY is high (depending

on the user’s settings).

In this condition, the watchdog timer can be disabled or enabled. If the watchdog timer is enabled, the timer needs to be cleared before the programmed count of the timer is reached. If the programmed count is reached, the STBY will be asserted.

Caution: It is advisable not to enable the watchdog timer during normal operation.

10/39

STFPC311 3 Initialization

3.6.3 Watchdog timer operation during standby

● When a hot-key signal is detected either from the front panel or remote control during

standby, the STBY de-asserts.

● The de-assertion of the STBY triggers the watchdog timer.

● The timer value is the programmed value that is set by the user (1s-15s). If the user did not

change the value before entering standby, then it remains 10s.

● Also note: that The watchdog timer is off when the STFPC311 is in the standby mode to

save power.

Figure 5. Standby condition

3a) Standby Condition (Normal behavior)

Hot key com mand from IR

or Key pad for wake up

STBY

W DG timer triggers

READY

MUTE

3b) Standby Condition (Abnormal behavior, processor is not responding)

Hot key com mand from IR

or Key pad for wake up

STBY

READY

MUTE

READY asserts within programm ed timer value (1 s-15s)

Signals STBY after

WDG timer

triggers

Signals STBY after W DG count is over

W DG count is over

REA DY continues to remain low

The watchdog timer is triggered by a de-assertion of the STBY signal or by the internal Power-on Reset signal. It is not affected by the STB pin.

11/39

3 Initialization STFPC311

3.7 Flow charts

Figure 6. Timing power standby sequencer flow chart

* Programmable from 1 to 15s.

† FPK = Front Panel Keys

12/39

STFPC311 3 Initialization

Figure 7. IR RC command and front panel key operation flowchart.

13/39

3 Initialization STFPC311

Figure 8. Watchdog timer first power-up operation

Figure 9. Watchdog timer operation

14/39

STFPC311 4 Display RAM address and display mode

4 Display RAM address and display mode

The display RAM stores the data transmitted from an external device to the STFPC311 through the serial interface and is assigned addresses, in units of 8-bits see :Table 2.

Only the lower 4 bits of the addresses assigned to Seg

through Seg20 are valid, the higher 4

17

bits are ignored.

Note: The common grid/segment outputs are grid-based. The grid has to be enabled before any

segments can be turned on. If data is written for a segment before enabling its grid, there is nothing on the display.

Table 2. Assigned addresses

Seg

1

00 H

03 H

06 H

09 H

0C H

0F H

12 H

15 H

18 H

1B H

1E H

21 H

24 H

27 H

2A H

2D H

b

0

XX H

Lower 4 bits Higher 4 bits

Seg

4

L

b3b

4

L

00 H

03 H

06 H

09 H

0C H

0F H

12 H

15 H

18 H

1B H

1E H

21 H

24 H

27 H

2A H

2D H

XX H

Seg

8

U

b

7

U

01 H

04 H

07 H

0A H

0D H

10 H

13 H

16 H

19 H

1C H

1F H

22 H

25 H

28 H

2B H

2E H

Seg

12

L

01 H

04 H

07 H

0A H

0D H

10 H

13 H

16 H

19 H

1C H

1F H

22 H

25 H

28 H

2B H

2E H

Seg

16

U

02 H

05 H

08 H

0B H

0E H

11 H

14 H

17 H

1A H

1D H

20 H

23 H

26 H

29 H

2C H

2F H

Seg

20

L

DIG

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

15/39

4 Display RAM address and display mode STFPC311

The data of each key is stored READ by a read command, starting from the least significant bit. see Figure 11..

When the most significant bit of data (Seg next data (Seg

) is read.

1b0

) has been read, the least significant bit of the

12b7

Figure 10. Key matrix (12 x 2 configuration) and key-input data storage RAM

Figure 11. Key storage and READ access

16/39

STFPC311 5 Data

5 Data

5.1 LED Port

Data is written to the LED port by a WRITE command, starting from the least significant bit of the port see Figure 12. When a bit of this port is set to 0, the corresponding LED lights up; when the bit is set to a 1, the LED turns off. The data of Bits 5 through 8 are ignored. Upon first power-up, all of the LEDs are turned off.

Figure 12. LED port data WRITE command order

5.2 SW Data

The SW data are read by the appropriate READ command, starting from the least significant bit see Figure 13. Bits 3 through 8 of the SW data are 0.

Figure 13. SW data READ Command order

17/39

6 Commands STFPC311

6 Commands

A command sets the display mode and status of the VFD driver. The first 1-byte input to the STFPC311 through the D set to high while commands/data are transmitted, the serial communication is initialized and the commands/data being transmitted are invalid (however, the commands/data already transmitted remain valid).

6.1 Configuration mode setting command

This command initializes the STFPC311 and performs any one of the following functions see

Figure 14.

a) Selects the number of segments and number of grids (1/8 to 1/16 duty, 12 segments

to 20 segments). When this command is executed, the display is turned off. To resume display, the Display ON command must be executed. If the same mode is selected, nothing is performed.

b) Selects the remote control protocol to use.

c) Sets the watchdog timer. The watchdog timer is configurable from 1s to 15s or turned

off completely.

d) Sets the watchdog action to perform when the watchdog timer counts. Two actions

are allowed: no action, and set STBY to (logic) high level.

pin after the STB pin goes low is regarded as a command. If STB is

IN

Figure 14. STFPC311 Configuration mode setting command order

Table 3. STFPC311 Configuration mode bit 3 through bit 0 settings

Note: Based on Bit 5 through Bit 4 settings.

18/39

STFPC311 6 Commands

Upon power application, the following modes are selected:

● Display Mode Setting: the 16-digit, 12-segment mode is selected (default: display off and

key-scan on).

● Remote Control Protocol Setting: RC-5.

● Watchdog Timer Setting: Turned on with 10s. After the first command is processed by

STFPC311, the watchdog timer is turned off until it is turned on by the host.

● Watchdog action: Issue Standby.

6.2 Data setting command

This command sets the data WRITE and READ modes see Figure 15.

Figure 15. STFPC311 Data setting command order

19/39

6 Commands STFPC311

When the application is powered-up, the normal operation mode and address increment mode is set with the default display memory address set to 00H. In the auto-increment address mode, the address command is sent once, followed by the data bytes.

Alternatively, the data command can be sent, followed by the data bytes. In this case, when new display data is to be written, the last value of the address will be used and then incremented. Upon reaching the last display memory address, the address jumps to 00H.

For fixed address mode, the address command has to be sent, followed by the display data. When next byte of data is to be written, the address command has to be sent again before the new display data byte.

For RC-5 data reception (after the photodiode), a binary 1 is represented by a high-to-low transition, and a binary 0 is represented by a low-to-high transition. For RC-6 (Mode 0) data reception, a binary 1 is represented by a low-to-high transition, and a binary 0 is represented by a high-to-low transition. Whenever Bit 5 is a ‘1’, the watchdog timer is reset.

6.3 Address setting command

This command sets an address of the display memory. If address 30H or higher is set, the data is ignored until a correct address is set.

Figure 16. STFPC311 Address Setting Command Order

6.4 Display control and hotkey setting command

When the application is powered-up, the 1/16-pulse width is set and the display is turned OFF.

See Figure 17 and Figure 4. All hot keys are disabled.

Figure 17. STFPC311 Display control and hot key setting command order

20/39

STFPC311 6 Commands

Table 4. STFPC311 Address setting mode bit 3 through bit 0 settings

21/39

7 Programmable hotkeys STFPC311

7 Programmable hotkeys

7.1 IR Remote control

Eight (8) commands are user programmable for hot key functions.

The address of the appliance (8-bit) is stored first into the internal RAM. Then, the command for the hot keys are programmed into the internal RAM. Each hot key memory address could accommodate one byte (8-bits). Usually one byte is reserved for one command. The RC data is only cleared when the READY is pulled low (system goes into STANDBY state).

7.2 Front panel keys

Eight out of 24 keys are user programmable for hot key functions. Only keys from KS1 to KS4 can be programmed.

Figure 18. Programmable hot keys (only KS1 to KS4, Box FPK1)

8 hot keys are to be placed in each address location as indicated by the hotkey setting command.

Figure 19. HOTKEY setting command address locations (8 hot keys)

For example, to store (Seg2/Key2) at the first location of the hot key RAM, the following commands are sent:

● 10110000 (command+address), and

● 00010000 (hot key mask).

To store (Seg2/Key1), (Seg2/Key2), and (Seg4/Key1), the following commands are sent:

● 10110000 (command+address), and

● 00110010 (hot key mask).

The same commands apply to FPK2 and FPK3 programming.

Note: Note: Reading the hot key values immediately upon STBY de-assertion is recommended. If

they are not read within the watchdog preset timer value, the hot key data is cleared.

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STFPC311 7 Programmable hotkeys

Figure 20. Recommended software flow

Note: Resetting the front panel controller at ¾ of the set watchdog time is recommended.

23/39

8 Default status STFPC311

8 Default status

8.1 Power-up default status

Table 5. Default States

S. N°

1Display OFF

2 Key-scan ON

3IR ON

4 Display mode 12 Seg/16Bit

5 Display address 00H

6 RC Protocol DC-5

7LED OFF

8 Dimming 1/16 Duty factor

9 Hot Kets (IR and FP) Disabled

10 Watchdog timer 10s

8.2 STANDBY status

The display remains ON during STANDBY only if the -20V is present. If the -20V is absent, the display turns OFF. When the display wakes up from STANDBY and –20V is applied, the display turns ON with previous value.

Switching off the display before entering the STANDBY state is recommended.

Functions Default Status

When the same display configuration command is sent, the display remains ON. When the display configuration command is changed, the display is OFF.

Only hot key detection can wake the system up from STANDBY condition.

24/39

STFPC311 9 Remote control protocols

9 Remote control protocols

9.1 RC-5 remote control

RC-5 remote control protocol is based on Bi-phase (also known as Manchester) encoding as shown in Figure 21.

Note: The encoding is set with reference to the IR_DATA_IN signal (after the photo diode). The MSB

is transmitted first see Figure 22.

● The first two Start bits (S1 and S2) are synchronization bits. For normal operation, they are

always set to '11' on the transmission side. After the photo diode, there is one inversion. The data at the IR_DATA_IN of the STFPC311 is shown in Figure 23 on page 25

● The next bit is the Toggle bit. This bit is inverted each time a key on the remote control is

pressed.

● Bits A1and A5 are the Address bits. The address bits indicate the intended application that

the remote control protocol is used for.

● Bits C1..C6 are the Command bits. The command bits instruct the STFPC311 as to what

action is to be taken. The data representing the RC-5 protocol is sent as a byte of data which consists of a Toggle bit and a ‘0’ bit followed by 6 bits of Command data.

Figure 21. Bi-phase encoding

Figure 22. RC-5 protocol frame

Figure 23. RC-5 reception example

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9 Remote control protocols STFPC311

9.2 SPI interface IR data transmission

The IR data is sent on the DOUT pin of the SPI interface when the micro controller issues a IR data read command. The data is sent in 3 bytes with LSB transmitted first as shown in the Figure below:

The RC data consists of RC address, start bit, toggle bit and the RC command received. The extra bits are stuffed with 1’s to make it a 3-byte packet. These extra bits at the end of the packet should be ignored.

Figure 24. RC-6 protocol frame

The RC data consists of RC address, start bit, toggle bit and the RC command received. The extra bits are stuffed with 1’s to make it a 3-byte packet. These extra bits at the end of the packet should be ignored.

9.3 NEC remote control

This remote control protocol uses pulse distance modulation. Each bit consists of a high level of fixed time "t", followed by a low level that varies in width. A space that is "t" represents a logic '0' and a space that is "3t" represents a logic '1'. t = 0.56ms.

The LSB is transmitted first as shown in Figure 25

Figure 25. Pulse distance modulation.

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STFPC311 9 Remote control protocols

Figure 26. NEC protocol transmission waveforms

27/39

10 Maximum rating STFPC311

10 Maximum rating

Stressing the device above the rating listed in the “Absolute Maximum Ratings” table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the Operating sections of this specification is not implied. Exposure to Absolute Maximum Rating conditions for extended periods may affect device reliability. Refer also to the STMicroelectronics SURE Program and other relevant quality documents.

Table 6. Absolute maximum rating ( T

= 25 °C, VSS = 0V )

A

Symbol Parameter Value Unit

V

DD

V

SS

V

O2

I

O1

I

O2

P

T

STG

1. Derate at -9.6 mW/°C at TA = 25 °C or higher

Logic Supply Voltage -0.5 to +7.0 V

+ 0.5 to V

Driver Supply Voltage

Logic Input Voltage

I1

VFP Driver Output Voltage

V

DD

-0.4 to V

V

SS

DD

– 0.5 to V

DD

+ 0.5

DD

LED Driver Output Current +25 mA

VFP Driver Output Current

Power Dissipation

D

Operating Ambient Temperature -40 to +85 °C

A

-40 (grid)

-15 (segment)

(1)

1200

Storage Temperature -65 to +150 °C

– 40

Table 7. Recommended operating conditions (TA = -20 to +70 °C, VSS = 0V)

Symbol Parameter Min Typ Max Unit

V

DD

V

SS

Logic Supply Voltage 3.0 3.3 3.6 V

High-Level Input Voltage

IH

Low-Level Input Voltage 0

IL

0.7V

DD

Driver Supply Voltage 0

V

0.3 V

V

DD

-33.3

V

mA

V

28/39

STFPC311 10 Maximum rating

10.1 Power consumption estimation

The maximum power consumption is comprised of the Vacuum Florescent Display (VFD) driver dissipation, Load Resistance (RL), LED driver dissipation, and dynamic power consumption.

P

= VFD + RL + LED + P

MAX

Where,

● P

● VFD = Vacuum Florescent Display driver dissipation,

● R

● LED = LED driver dissipation, and

● PDYN = dynamic power consumption.

= maximum power consumption,

MAX

= load resistance,

L

If the segment current (ISEG) = 3mA, grid current (IGRID) = 15mA, and the LED current = 20mA, then:

FIP = (#segments x 6) + [#grids/(#grids +1)] x 30mW,

RL dissipation = (VDD – VSS)2 ÷ 50(segment + 1mW),

LED driver dissipation = #LEDs x 20mW, and

PDYN = VDD x 5mW.

To finish this example:

FIP driver dissipation = 16 x 6 + 12/13 x 30 = 124mW

RL dissipation = 33.32/50 x 17 = 377mW

LED driver dissipation = 2 x 20 = 40

PDYN = 3.3 x 5 = 16.5mW

DYN

The maximum power consumption (Total) = 557.5mW

Where,

VSS = –30V,

VDD = 3.3V, and the application is in 16-segment, 12-digit mode.

29/39

11 Electrical characteristics STFPC311

11 Electrical characteristics

Table 8. Electrical specifications

(T

= -20 to +70°C, VDD = 3.3V, VSS = 0V, V

A

Symbol Parameter Test conditions Min. Typ. Max. Unit

SS

= V

DD

- 33.3V)

V

I

OH21

I

OH22

I

OLEAK

High-Level Output Voltage

OH1

Low-Level Output Voltage

OL1

Low-Level Output Voltage

OL2

High-Level Output Current

Driver Leakage Current

R

Output Pull-Down Resistor Driver output 50 100 150 kΩ

L

I Input Current

V

High-Level Input Voltage

IH

V

Low-Level Input Voltage

IL

V

Hysteresis Voltage

H

I

DD(DYN)

Dynamic Current Consumption

LED1 – LED4, I

, I

D

V

V Se

V

OUT

O

13

O

= 4mA

OL2

= V

– 2V, Seg

DD

= V

– 2 V, Grid

DD

g/Grid16to Seg20/Grid

= V

– 33.3 V, driver off

DD

VI= VDD or V

CLK, D

, STB

IN

Under no load, display off 5 mA

Table 9. Switching characteristics (TA = -20 to +70 °C, V

= -1mA 0.9V

OH1

= 20mA

OH2

to Seg

1

to Grid8,

1

SS

12

9

DD

-3 mA

-15 mA

0.7V

DD

0.35 V

= 3.3 V, V

DD

= -30 V)

SS

1V

0.4 V

-10 µA

±1 µA

0.3V

DD

Symbol Parameter Test conditions Min. Typ. Max. Unit

V

t

TZH1

t

TZH2

t

f

Oscillation Frequency R = 33KΩ ±5% 350 500 650 kHz

OSC

PLZ

Propagation Delay Time

PZL

Rise Time

Fall Time

THZ

Maximum Clock

MAX

Frequency

C

Input Capacitance 15 pF

I

CLK ≤ D

CL = 15pF, RL = 10KΩ

C

= 300pF

L

C

= 300pF, Segn, Grid

L

Duty = 50% 1 MHz

30/39

OUT

Seg

to Seg

1

12

Grid1 to Grid8,

/Seg16 to

Seg

13

/Grid

Seg

20

9

n

300 ns

100 ns

2 µs

0.5 µs

120 µs

STFPC311 12 Timing characteristics

12 Timing characteristics

Table 10. Timing characteristics ( VDD= 3.3V, TA= -20 to 70°C, unless otherwise noted.

Typical values are at T

Symbol Parameter Test conditions

= 25°C )

A

Values

Unit

Min. Typ. Max.

PW

t

SETUP

t

HOLD

t

CLK-STB

t

WAIT

1. Refer to page on Serial Communication Format.

Clock Pulse Width 400 ns

CLK

Strobe Pulse Width 1 µs

STB

Data Setup Time 100 ns

Data Hold Time 100 ns

Clock-Strobe Time CLK STB 1 µs

Wait Time

(1)

CLK CLK 1 µs

The pulse width of the segment signal is derived from the oscillator frequency. The value can be modified by trimming ROSC. One cycle of key scanning consists of one frame and data of 12 x 2 matrices are stored in RAM.

Note: The key scan is only at the end of the frame when the display is ON. When the display is OFF,

the key scan takes place continuously. The grid is turned off during the key scan.

Figure 27. Key scanning and display timing

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13 Serial communication format STFPC311

13 Serial communication format

When data is read, a wait time (t clock that has set the command, and the falling edge of the first clock that has read the data. This is required by the STFPC311 to process its internal commands/data (See Figure 28)

Caution: Care must be taken to connect an external pull-up resistor to this pin (1kΩ to 10kΩ) because the

D

pin is an N-channel, open drain output pin (see Figure 29).

OUT

Figure 28. Recption (Command/data WRITE)

) of 1µs is necessary within the rising edge of the eighth

WAIT

Figure 29. Data transmission (data READ)

32/39

STFPC311 13 Serial communication format

Figure 30. Switching characteristic waveforms

f

OSC

50%

PW

STB

CLK

D

IN

D

OUT

Sn/G

PW

CLK

t

SETUP

90%

n

10%

PW

t

HOLD

CLK

t

THZ

t

CLK-STB

t

PZL

t

TZH

t

PLZ

33/39

13 Serial communication format STFPC311

● Command 1: sets display mode

● Command 2: sets data

● Command 3: sets address

● Data 1 to n: transfers display data (22 bytes max.)

● Command 4: controls display

Figure 31. Updating display memory by incrementing address

● Command 1: sets data

● Command 2: sets address

● Data: display area

Figure 32. Updating specific address

34/39

STFPC311 14 Typical application diagram

14 Typical application diagram

Figure 33. Typical application circuit

R5

R6

+

C1

R6

D1

V

DD

C2

1

<

2

<

3

<

4

<

5

<

6

<

7

<

8

<

9

<

10

VDD3.3V±0.3V

11

12

VDD3.3V±0.3V

VSS* -30V

GND

<

< <

<

R

OSC

KEY1 KEY2

V

DD

OSC

STB

CLK

D

IN

D

OUT

IR_DATA_IN

READY/STBY_n

NC

MUTE

MUTE STBY

STBY

SEG1/K1

STFPC311

12 x 2

KEYBOARD

V

SS

D12

SEG12/K12

S13/G16 ~ S20/G9

G1 ~ G8

LED1

LED2

LED3

LED4

V

SS

C3 C4

+

8 Grids/Segments

8 Grids

R1

R2

R3

R4

V

DD

VFD

Ef

● R

= 33kΩ ± 1% for oscillator resistor;

OSC

● R1 ~ R4 = 0.75 ~ 1.2kΩ;

● R5, R6 = 10kΩ for external keyboard pull-down resistor;

● C1 = 33µF-25V electrolytic;

● C2 = 0.01 ~ 0.1µF-25V ceramic;

● C3 = 0.01 ~ 0.1µF-63V ceramic;

● C4 = 33µF-63V electrolytic;

● D1 ~ D12 = 1N4148;

● Ef = filament voltage according with the VFD specs;

● V

* V

= 3.3V ±10%;

DD

= down to VDD – 33.3V.

SS

35/39

15 Package mechanical data STFPC311

15 Package mechanical data

In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a Lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at:

www.st.com.

36/39

STFPC311 15 Package mechanical data

Table 11. PQFP52 - 10x10x2 mm. plastic quad flatpack, package mechanical data

Figure 34. Package dimensions

37/39

16 Revision history STFPC311

16 Revision history

Table 12. Revision history

Date Revision Change

09-May-2006 1 First release

38/39

STFPC311 16 Revision history

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39/39

ST STFPC311 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

1 Functional description

1.1 Block diagram

2 Pin connection

2.1 Pin description

3 Initialization

3.1 Normal mode of operation

3.2 Receive operation

3.3 Transmit operation

3.4 Standby or power-down mode

3.5 IR Decoding

3.6 Watchdog timer

3.6.1 Watchdog timer operation during power-up

3.6.2 Watchdog timer operation during power-down

3.6.3 Watchdog timer operation during standby

3.7 Flow charts

STFPC311 4 Display RAM address and display mode

5 Data

5.1 LED Port

5.2 SW Data

6 Commands

6.1 Configuration mode setting command

6.2 Data setting command

6.3 Address setting command

6.4 Display control and hotkey setting command

7 Programmable hotkeys

7.1 IR Remote control

7.2 Front panel keys

8 Default status

8.1 Power-up default status

8.2 STANDBY status

STFPC311 9 Remote control protocols

9.1 RC-5 remote control

9.2 SPI interface IR data transmission

9.3 NEC remote control

10 Maximum rating

10.1 Power consumption estimation

11 Electrical characteristics

12 Timing characteristics

13 Serial communication format STFPC311

STFPC311 14 Typical application diagram

15 Package mechanical data STFPC311

16 Revision history