STM8S datasheet(58/467 Pages) STMICROELECTRONICS

58 / 467 page

Single wire interface module (SWIM) and debug module (DM)

RM0016

58/467

DocID14587 Rev 14

There are two important considerations to highlight for the devices where the NRST pin is

not present:

•

If the SWIM pin should be used with the I/O pin functionality, it is recommended to add

a ~5 seconds delay in the firmware before changing the functionality on the pin with

SWIM functions. This action allows the user to set the device into SWIM mode after the

device power on and to be able to reprogram the device. If the pin with SWIM

functionality is set to I/O mode immediately after the device reset, the device is unable

to connect through the SWIM interface and it will be locked forever (if the NRST pin is

not available on the package). This initial delay can be removed in the final (locked)

code.

•

Their program memory must contain a valid program loop. If the device's memory is

empty, the program continues into non-existing memory space and executes invalid

opcode; this causes the device to reset (reading of non-existing memory is random

content). This behavior might lead to periodic device resets and to a difficulty to

connect to the device through the SWIM interface.

STM8S Arkusz danych(PDF) 58 Page - STMicroelectronics