Programming STM8 Flash microcontrollers

PM0051

24/27

Doc ID 14614 Rev 3

4.6.1

ICP methods

The in-circuit programming (ICP) method is used to update the content of Flash program

memory and data EEPROM.

The programming interface for STM8 devices is the SWIM (Single Wire Interface Module). It

is used to communicate with an external programming device connected via a cable.

See STM8 SWIM communication protocol and debug module user manual (UM0470) for

more details on the SWIM mode entry and SWIM protocol.

When using the SWIM protocol, two methods can be used:

First method

The first method consists of writing directly into the Flash registers and memory locations

through the write memory command of the SWIM protocol. To make sure that the CPU is

not accessing the memory during block Flash programming, the core must be stalled by

setting the STALL bit in the DM_CSR2 debug module register.

The following sequence is required:

1.

Apply a RESET

2.

Activate the SWIM by sending the entry sequence on the SWIM pin

3.

Activate the SWIM_CSR register by writing 1 to the DM bit in SWIM_CSR

4.

Disable interrupts by setting the SAFE_MASK bit in SWIM_CSR

5.

Release RESET

6.

Verify the DeviceID by reading it using ROTF command

7.

Send the SWIM SRST command

8.

Unlock the memory by writing the MASS keys

9.

Program the Flash program memory using the SWIM WOTF command

Second method

The second method uses the same sequence of operations as the first method except that

the ICP driver firmware must be downloaded in RAM before being launched:

1.

Apply a RESET

2.

Activate the SWIM by sending the entry sequence on the SWIM pin

3.

Activate the SWIM_CSR register by writing 1 to the DM bit in SWIM_CSR

4.

Disable interrupts by setting the SAFE_MASK bit in SWIM_CSR

5.

Release RESET

6.

Verify the DeviceID by reading it using ROTF command

7.

Send the SWIM SRST command

8.

Unlock the memory by writing the MASS keys

9.

Download the ICP driver firmware into the device RAM using the SWIM WOTF

command

10. Execute the ICP driver:

a)

Modify the CPU registers (new PC, X, Y, CC...) using the WOTF commands

b)

Set the FLASH bit in the DM_CSR2 register

c)

Clear the STALL bit in the DM_CSR2 register