Programming STM8 Flash microcontrollers

PM0212

12/22

Doc ID 022351 Rev 2

4

Programming STM8 Flash microcontrollers

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

4.1

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 3.4: Unwanted memory access

protection, and Table 4: MASS.

The software must poll the PUL and DUL bit, before attempting to write to program memory

and data EEPROM, respectively.

4.2

Block programming

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

programming time.

There are three possible 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.

The memory must be unlocked before performing any of these operations.

Table 4.

MASS

Microcontroller

family

Data EEPROM and option bytes

Program memory

Unlock

Lock

Unlock

Lock

STM8TL5xxx

Write 0xAE then

56h in

FLASH_DUKR

1.

In STM8TL5xxx 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)