The use of the ‘M’ command and stable power supply it normally the challenge in these cases.
During the ‘M’ comnmand part of the flash is erase and rewritten. In case of the power supply being turn off at this stage
or limited current capability of VCC this could leave this part of flash in unknown state.
This will make the module seem dead.
1) Limit the use of ‘M’ command to once. (normally in factory and not in field)
2) Make sure that VCC supply and VCC_PA cupply can handle the current without voltage drops.
a. E.g. Some LDO’s have large voltage drop during pulse current. When we erase flash with M-Command it is a pusle current used.
3) Never turn power off close to an ‘M’ command in time.
Last Update: August 8, 2017