PM0054

Programming STM8 Flash microcontrollers

Doc ID 15433 Rev 9

17/28

5

Programming STM8 Flash microcontrollers

This section describes how to program STM8 single-voltage Flash microcontrollers.

5.1

Unlocking the memory access security system (MASS)

The memory must be unlocked before attempting to perform any erase or write operation.

To unlock it, follow the procedure described in Section 4.4: Unwanted memory access

protection, and Table 9. The software must poll the PUL and DUL bit, before attempting to

write to program memory and data EEPROM, respectively.

5.2

Block programming

Block write operations can program an entire block in one shot, thus minimizing the

programming time. There are three block programming modes: erase, write only (also called

fast programming) and combined erase/write cycle (also called standard block

programming). The programming mode is selected through FLASH_CR2 register.

Block program operations can be performed both to main program memory and DATA area:

●

Programming a block of main program memory:

–

The block program operation has to be executed totally from RAM.

–

The program execution continues from RAM. If the program goes back to main

program memory, it is stalled until the block program operation is complete. On

medium and medium+ density STM8L15x and high density STM8L05x/15x/16x,

the DMA controller can be programmed to perform a block transfer to Flash

program memory, and put the CPU in Wait mode.

●

Programming a block of data EEPROM with RWW capability:

–

The block program operation can be executed from main program memory.

However the data loading phase has to be executed from RAM (see below).

–

Normal program execution can continue from main program memory. The HVOFF

bit of the FLASH_IAPSR register can be polled to check if the memory is ready for

RWW.

●

Programming a block of data EEPROM without RWW capability:

The block program operation must be executed totally from RAM.

Table 9.

MASS

Microcontroller

family

Data EEPROM and option bytes

Program memory

Unlock

Lock

Unlock

Lock

STM8L / STM8AL

Write 0xAE then

56h in

FLASH_DUKR

1.

In the low density STM8L101x devices the option bytes are not accessible in user/IAP mode.

2.

The OPT bit of the FLASH_CR2 register must be set/cleared to enable access to the option bytes.

Reset bit 3 (DUL)

in FLASH_IAPSR

(0x00 5054)

Write 0x56 then

0xAE in

FLASH_PUKR

3.

If wrong keys have been entered, a reset must to be generated to be able to reprogram the right keys.

Reset bit 1 (PUL)

in FLASH_IAPSR

(0x00 5054)