1. See Package mechanical data section for package dimensions, and how to identify pin-1.
Doc ID 022470 Rev 17/35
Signal descriptionM95160-145
2 Signal description
During all operations, VCC must be held stable and within the specified valid range:
V
(min) to VCC(max).
CC
All of the input and output signals must be held high or low (according to voltages of V
V
, VIL or VOL, as specified in Ta bl e 1 0 . These signals are described next.
OH
2.1 Serial Data output (Q)
This output signal is used to transfer data serially out of the device. Data is shifted out on the
falling edge of Serial Clock (C).
2.2 Serial Data input (D)
This input signal is used to transfer data serially into the device. It receives instructions,
addresses, and the data to be written. Values are latched on the rising edge of Serial Clock
(C).
,
IH
2.3 Serial Clock (C)
This input signal provides the timing of the serial interface. Instructions, addresses, or data
present at Serial Data Input (D) are latched on the rising edge of Serial Clock (C). Data on
Serial Data Output (Q) changes after the falling edge of Serial Clock (C).
2.4 Chip Select (S)
When this input signal is high, the device is deselected and Serial Data Output (Q) is at high
impedance. Unless an internal Write cycle is in progress, the device will be in the Standby
Power mode. Driving Chip Select (S
mode.
After Power-up, a falling edge on Chip Select (S
instruction.
2.5 Hold (HOLD)
The Hold (HOLD) signal is used to pause any serial communications with the device without
deselecting the device.
2.6 Write Protect (W)
) low selects the device, placing it in the Active Power
) is required prior to the start of any
The main purpose of this input signal is to freeze the size of the area of memory that is
protected against Write instructions (as specified by the values in the BP1 and BP0 bits of
the Status Register).
This pin must be driven either high or low, and must be stable during all write instructions.
8/35Doc ID 022470 Rev 1
M95160-145Signal description
2.7 VCC supply voltage
VCC is the supply voltage.
2.8 VSS ground
VSS is the reference for the VCC supply voltage.
Doc ID 022470 Rev 19/35
Implementing devices on the SPI busM95160-145
3 Implementing devices on the SPI bus
Figure 3 shows an example of three devices, connected to the SPI bus master. Only one
device is selected at a time, so that only the selected device drives the Serial Data output
(Q) line. All the other devices outputs are then in high impedance.
Figure 3.Bus master and memory devices on the SPI bus
6
##
30)INTERFACEWITH
#0/,#0(!
OR
30)BUSMASTER
#3 #3 #3
1. The Write Protect (W) and Hold (HOLD) signals must be driven high or low as appropriate.
A pull-up resistor connected on each S input (represented in Figure 3) ensures that each
device is not selected if the bus master leaves the S
3.1 SPI modes
3$/
3$)
3#+
6
##
222
30)MEMORY
DEVICE
3
7
(/,$
#1$#1$
30)MEMORY
3
DEVICE
7
6
(/,$
##
#1$
30)MEMORY
line in the high impedance state.
DEVICE
3
7
6
##
(/,$
6
33
-36
These devices can be driven by a microcontroller with its SPI peripheral running in either of
the two following modes:
●CPOL=0, CPHA=0
●CPOL=1, CPHA=1
For these two modes, input data is latched in on the rising edge of Serial Clock (C), and
output data is available from the falling edge of Serial Clock (C).
The difference between the two modes, as shown in Figure 4, is the clock polarity when the
bus master is in Stand-by mode and not transferring data:
●C remains at 0 for (CPOL=0, CPHA=0)
●C remains at 1 for (CPOL=1, CPHA=1)
10/35Doc ID 022470 Rev 1
M95160-145Implementing devices on the SPI bus
AI01438B
C
MSB
CPHA
D
0
1
CPOL
0
1
Q
C
MSB
Figure 4.SPI modes supported
Doc ID 022470 Rev 111/35
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