diff options
| author | iabdalkader | 2020-12-08 01:55:50 +0200 |
|---|---|---|
| committer | Damien George | 2020-12-17 23:19:25 +1100 |
| commit | b603066bc2d272d05033705922e515d50318e735 (patch) | |
| tree | 50b2fdd4aedc9fbbecbe7d815c5d2cc5afad7503 | |
| parent | 32d76e5de66237eba456975095f998434413467a (diff) | |
stm32/sdram: Add SDRAM enter/leave self-refresh mode functions.
These functions enable SDRAM data retention in stop mode. Example usage,
in mpconfigboard.h:
#define MICROPY_BOARD_ENTER_STOP sdram_enter_low_power();
#define MICROPY_BOARD_LEAVE_STOP sdram_leave_low_power();
| -rw-r--r-- | ports/stm32/sdram.c | 22 | ||||
| -rw-r--r-- | ports/stm32/sdram.h | 2 |
2 files changed, 22 insertions, 2 deletions
diff --git a/ports/stm32/sdram.c b/ports/stm32/sdram.c index 0aae74e11..e8892b574 100644 --- a/ports/stm32/sdram.c +++ b/ports/stm32/sdram.c @@ -49,8 +49,7 @@ #ifdef FMC_SDRAM_BANK -static void sdram_init_seq(SDRAM_HandleTypeDef - *hsdram, FMC_SDRAM_CommandTypeDef *command); +static void sdram_init_seq(SDRAM_HandleTypeDef *hsdram, FMC_SDRAM_CommandTypeDef *command); extern void __fatal_error(const char *msg); bool sdram_init(void) { @@ -254,6 +253,25 @@ static void sdram_init_seq(SDRAM_HandleTypeDef #endif } +void sdram_enter_low_power(void) { + // Enter self-refresh mode. + // In self-refresh mode the SDRAM retains data with external clocking. + FMC_SDRAM_DEVICE->SDCMR |= (FMC_SDRAM_CMD_SELFREFRESH_MODE | // Command Mode + FMC_SDRAM_CMD_TARGET_BANK | // Command Target + (0 << 5U) | // Auto Refresh Number -1 + (0 << 9U)); // Mode Register Definition +} + +void sdram_leave_low_power(void) { + // Exit self-refresh mode. + // Self-refresh mode is exited when the device is accessed or the mode bits are + // set to Normal mode, so technically it's not necessary to call this functions. + FMC_SDRAM_DEVICE->SDCMR |= (FMC_SDRAM_CMD_NORMAL_MODE | // Command Mode + FMC_SDRAM_CMD_TARGET_BANK | // Command Target + (0 << 5U) | // Auto Refresh Number - 1 + (0 << 9U)); // Mode Register Definition +} + bool sdram_test(bool fast) { uint8_t const pattern = 0xaa; uint8_t const antipattern = 0x55; diff --git a/ports/stm32/sdram.h b/ports/stm32/sdram.h index 9b4b4fb83..773a30802 100644 --- a/ports/stm32/sdram.h +++ b/ports/stm32/sdram.h @@ -11,5 +11,7 @@ bool sdram_init(void); void *sdram_start(void); void *sdram_end(void); +void sdram_enter_low_power(void); +void sdram_leave_low_power(void); bool sdram_test(bool fast); #endif // __SDRAM_H__ |