st92f124 STMicroelectronics, st92f124 Datasheet - Page 408

• Manufacturer Part Number: st92f124
• Description: 8/16-bit Single Voltage Flash Mcu Family With Ram, E3 Tmemulated Eeprom, Can 2.0b And J1850 Blpd
• Manufacturer: STMicroelectronics

ST92F124/F150/F250 - KNOWN LIMITATIONS
KNOWN LIMITATIONS (Cont’d)
13.1.2 FLASH CORRUPTION WHEN EXITING
STOP MODE
Description
Under very specific conditions, the first read per-
formed in flash memory by the core when exiting
stop mode may be corrupted.
Impact on application
As this first read is an opcode, this corruption may
lead to an unpredictable behavior of the applica-
tion.
RRx is an unused register in the register file.
Implementation
And replace the actual STOP bit setting sequence
(specified in datasheet):
408/426
1
nop
ldw RRx,0
WU_CTLR = WUm_wuit | WUm_id1s | WUm_stop;
WU_CTLR = WUm_wuit | WUm_id1s;
WU_CTLR = WUm_wuit | WUm_id1s | WUm_stop;
#pragma register_file
volatile unsigned int
spp(WU_PG);
asm("nop");
asm("nop");
asm("nop");
Dummy_16bit_data
Dummy_16bit_data;
Workaround
Description
In ST92F124/F150/F250 datasheet, there is a
warning in the WUCTRL register description:
“In order to avoid to execute register write instruc-
tions after a correct STOP bit setting sequence
and before entering the STOP mode, it is manda-
tory to execute 3 NOP instructions after the STOP
bit setting sequence.”
The workaround is to replace these 3 NOPs by the
following assembly code:
In a C language software, implement the following
code.
Declare a dummy variable in the register file (for
example in RR0 16-bit register)
0