Programming STM8 Flash microcontrollers

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Note:

1

The mechanism to lock and unlock unwanted memory access protection is identical for

option bytes and data EEPROM (see Table 7: MASS).

2

Before starting programming program memory or data EEPROM, the software must verify

that the area is not write protected by checking that the PUL or DUL bit is effectively set.

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 3.3: Unwanted memory access

protection, and Table 7.

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).

Table 7.

MASS

Microcontroller

family

Data EEPROM and option bytes

Program memory

Unlock

Lock

Unlock

Lock

STM8S and

STM8A

Write 0xAE then

56h in

FLASH_DUKR

1.

The OPT and NOPT bits of FLASH_CR2 and FLASH_NCR2 registers must be set/cleared to enable

access to the option bytes.

2.

If wrong keys have been entered, another key programming sequence can be issued without resetting the

device.

Reset bit 3 (DUL)

in FLASH_IAPSR

(0x00 505F)

Write 0x56 then

0xAE in

FLASH_PUKR

3.

If wrong keys have been entered, the device must be reset, and a key program sequence issued.

Reset bit 1 (PUL)

in FLASH_IAPSR

(0x00 505F)