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AN2078
Application note
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ST AN2078 Application note

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AN2078
Application note
STR7 In-Application Programming using UART
Introduction
An important requirement for most Flash-based systems is the ability to update firmware while the system is installed in the end product. This is referred to as In-Application Programming (IAP).
This application note outlines general guidelines for creating an IAP application. The STR7xx Eval Boards were used to validate the IAP driver.
Software is provided and is available on http://www.st.com/mcu
January 2007 Rev 3 1/13
www.st.com
Contents AN2078
Contents
1 IAP overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 IAP driver description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Running the IAP driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 HyperTerminal configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Triggering execution of the IAP driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 IAP driver menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 Download image to internal Flash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2 Execute the new program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 STR7xx IAP implementation Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 User program conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6 IAP restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7 How to use the IAP driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
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AN2078 IAP overview

1 IAP overview

1.1 Principle

The IAP driver must be programmed by the user in the Flash base address (0x00) via JTAG using a flasher toolset.
Using the UART, the IAP driver loads a binary file from the HyperTerminal to the STR7xx internal Flash, and then jumps to execute it.

1.2 IAP driver description

The following table shows the IAP driver code size for each STR7xx MCU.
STR71x STR73x STR75x
7.2 Kbytes 8.3 Kbytes 5.8 Kbytes
The IAP driver contains a set of source files:
● main.c: where the UART initialization and PLL configuration are set. Then, a main
menu is executed from the common.c file.
● common.c: contains display functions and the main menu routine. The main menu
gives the choice between loading a new binary file and executing the binary file already loaded.
● ymodem.c and download.c: they allow all data to be received from the HyperTerminal
application (using the YMODEM protocol the event of a failure in data receival, the ‘Failed to receive the file’ error message is displayed on the HyperTerminal window. However, if successful, the data is then programmed into internal Flash at the appropriate address. A comparison between internal RAM and internal Flash contents is performed to check the data intergrity. If there is any discrepency, the ‘Verification failed’ error message is displayed on HyperTerminal window. Other error messages are also displayed when the image size is higher than the allowed space memory and when there is an abort by the user.
1)
), then loaded into STR7 internal RAM. In
Note: 1 Ymodem protocol sends data in 1024-byte blocks. A check for errors in data blocks
transmitted to the STR7xx Internal RAM is applied: A comparison between the transmitted and received data is achieved. Blocks received unsuccessfully are acknowledged with a NAK (Negative Acknowledgement). For more details about the Ymodem protocol, refer to existing documentation.
● Some STR7xx Standard library and Flash library files.
A pin connected to a push button is used to select between jumping to the user application and executing the IAP for reprogramming purpose:
● Push button is not pressed at reset: jump to the user application
● Push button is pressed at reset: the IAP main menu is displayed
Figure 1 shows the IAP flowchart.
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IAP overview AN2078
Figure 1. FlowChart of the IAP Driver
Start
Initialize the STR7 UART & PLL
Display the IAP Main Menu
Download
Receive a binary file
No
Success
Yes
Program the internal Flash
Push button is
pressed?
Yes
Download or
Jump?
No
Jump to User Program
Jump to the User Program
Display the error message ‘Failed
to receive the
file’
No
All data
programmed
successfully?
Yes
Display the name and the size of
the received file
Display the error message ‘Verfification failed’
User Application
Software
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AN2078 Running the IAP driver

2 Running the IAP driver

To run the IAP driver, STR7xx internal Flash must be hardware remapped at address 0x0. Thus the IAP driver is programmed in Flash bank0 sector0 and the user application in the remaining memory space in bank0.

2.1 HyperTerminal configuration

The IAP requires a PC running HyperTerminal with the following settings:
Figure 2. COM Port Properties
Note: A baud rate value of 115200 bps is used as an example.
Care should be taken when selecting the system clock frequency. Ensure that with the system clock frequency used in your application, you are able to generate a baud rate equal to 115200 bps in order to guarantee successful communication via UART.

2.2 Triggering execution of the IAP driver

In this application note, depending on the micro eval board, pins connected to push buttons are used as an example, allowing execution of the IAP driver. By keeping the push button pressed at reset, the user is able to run the IAP driver to reprogram the STR7xx internal Flash.
It is not mandatory to use push buttons and the user can simply enter signals on these pins with respect to their corrsponding active levels. Refer to the table in Section 4 on page 7 for the correct pins and their active levels for each MCU.
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IAP driver menu AN2078

3 IAP driver menu

The execution of the IAP firmware results in the following menu displayed in the HyperTerminal window.
Figure 3. IAP Driver menu

3.1 Download image to internal Flash

To download a binary file via HyperTerminal to the STR7xx internal Flash, follow the following procedure:
● Press “1” on the keyboard to choose the menu “Download Image To Internal Flash”
Now, in the Transfer menu, select “Send File”:
● In the filename field, type the name and the path of the binary file you want to send.
● In the protocol list, choose the Ymodem protocol,
● Click the “Send” button.
Following these steps, the IAP driver loads the binary file into the STR7xx internal Flash from bank0 sector1 base address and displays the binary file name and file size in the HyperTerminal window.

3.2 Execute the new program

After loading the new program from HyperTerminal by selecting the “Download Image To Internal Flash” menu, you can execute your code by selecting the “Execute The New Program” menu by pressing “2“ from the keyboard.
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AN2078 STR7xx IAP implementation Summary

4 STR7xx IAP implementation Summary

A summary of the STR7xx IAP implementation is described in the below table :
STR71x STR73x STR75x
IAP driver location 0x40000000 0x80000000 0x20000000
User application location
Flash remapping For STR7xx devices, the Flash must be hardware remapped at address 0x00.
Push button Active Level
Flash routines
UART used UART0
0x40002000 0x80002000 0x20002000
P1.8 (SEL)
0
For STR7xx devices, Flash routines (program/ erase) must be executed from RAM given that read-while-write operations in one Bank are not allowed. So, program/erase operations are performed from RAM.
P5.10 (SEL)
1
P1.05 (KEY)
0
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User program conditions AN2078

5 User program conditions

On STR7xx MCUs, the IAP driver should be programmed at the Flash base address (sector0 base address) and the user application should be programmed from bank0 sector1 base address. If the application to be programmed to the STR7xx internal Flash uses interrupts, it should provide software remapping of RAM to address 0x0 and also the exception vectors should be copied to this same address as illustrated in Figure 4.
Figure 4. STR7xx memory remapping conditions
FLASH
IAP Driver
0x0
User code exception
RAM
vectors
Bank0 Sector0 Base Address
Bank0 Sector1 Base Address
Remap RAM to 0x0
then copy the exception vectors
User Code
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AN2078 IAP restrictions

6 IAP restrictions

The STR7xx IAP driver code is downloaded to the bank0 sector0. So, the maximum size of the image to be loaded is 248 Kbytes (bank 0 size - sector 0 size).
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How to use the IAP driver AN2078

7 How to use the IAP driver

The IAP package consists of an archived file containing 6 subfolders:
● common: It contains the files commonly used by the STR7xx MCUs.
● stdlib: It contains the STR7xx standard libraries.
● flashlib: The STR7xx Flash library which is a set of C routines containing everything
needed to program the embedded Flash of STR7xx devices.
● str71x demo: It contains the main application and a project.
● str73x demo: It contains the main application and a project.
● str75x demo: It contains the main application and a project.
The file structure is described in the following figure:
Figure 5. IAP driver directory structure
Current Directory
common
stdlib
flashlib
str71x demo
str73x demo
include
source
str71x
str73x
str75x
inc
src
include
Project
source
include
Project
source
inc
inc
inc
src
src
src
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str75x demo
include
Project
source
AN2078 How to use the IAP driver
To efficiently use the IAP driver, please follow the different steps below:
● Download the IAP driver into the STR7xx internal Flash via JTAG using a Flasher
toolset.
● Open an HyperTerminal Window with the settings already defined in Section 2.1
● To run the IAP driver, keep the push button (according to the used STR7xx Eval board)
pressed at Reset. The IAP main menu is then displayed on the HyperTerminal window.
● To download an application, press 1 and use the YMODEM protocol as described in
Section 3.1.
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Revision history AN2078

8 Revision history

Table 1. Revision history
Date Revision Description of changes
31-Jan-2005 1 First release
Updated Introduction on page 1 Updated Figure 1 on page 4 Updated Section 2: Running the IAP driver on page 5 Updated Figure 3 on page 6
28-Feb-2006 2
12-Jan-2007 3 Document expanded to encompass STR71x, STR73x, STR75x.
Updated Section 3.1: Download image to internal Flash on page 6 Added new section: Section 3.2: Execute the new program on
page 6
Updated Section 5: User program conditions on page 8 IAP Driver updated to load up to 248 KBytes Updated Section 1: IAP overview on page 3
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AN2078 Revision history
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