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twai: Add errata workaround for listen only mode

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This commit adds a workaround for the TWAI listen only mode errata which is
present on the ESP32, ESP32-S2, ESP32-S3, and ESP32-C3. twai_get_status_info()
has also been updated to account for the fact that TEC/REC are frozen in
listen only mode.

Errata Description:

When the TWAI controller is put into listen only mode, it should not influence
the TWAI bus in any way (i.e., should never send a dominant bit). However,
on the targets listed above, the TWAI controller will send dominant bits in an
error frame (i.e., active error frame), even if the controller is set to listen
only mode.

Workaround:

We can force the TWAI controller into the error passive state on startup (by
setting the REC to >= 128). Since the TEC/REC are frozen in listen only mode,
the TWAI controller will remain error passive and only send recessive bits
(i.e., passive error frames), thus will not influence the TWAI bus.

Closes https://github.com/espressif/esp-idf/issues/9157
This commit is contained in:
Darian Leung 2023-02-22 20:42:55 +08:00
parent f3f3e87ea2
commit 72becf31e4
3 changed files with 34 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
components/driver/Kconfig
View File

@ -173,6 +173,17 @@ menu "Driver Configurations"
on detection of this errata condition. Note that if a frame is being sent on the bus during the reset
bus during the reset, the message will be lost.
config TWAI_ERRATA_FIX_LISTEN_ONLY_DOM
bool "Add SW workaround for listen only transmits dominant bit errata"
depends on IDF_TARGET_ESP32 || IDF_TARGET_ESP32S2 || IDF_TARGET_ESP32S3 || IDF_TARGET_ESP32C3
default y
help
When in the listen only mode, the TWAI controller must not influence the TWAI bus (i.e., must not send
any dominant bits). However, while in listen only mode on the ESP32/ESP32-S2/ESP32-S3/ESP32-C3, the
TWAI controller will still transmit dominant bits when it detects an error (i.e., as part of an active
error frame). Enabling this option will add a workaround that forces the TWAI controller into an error
passive state on initialization, thus preventing any dominant bits from being sent.
endmenu # TWAI Configuration
menu "Temperature sensor Configuration"

10
components/driver/twai/twai.c
View File

@ -725,8 +725,14 @@ esp_err_t twai_get_status_info(twai_status_info_t *status_info)
TWAI_CHECK(status_info != NULL, ESP_ERR_INVALID_ARG);
TWAI_ENTER_CRITICAL();
status_info->tx_error_counter = twai_hal_get_tec(&twai_context);
status_info->rx_error_counter = twai_hal_get_rec(&twai_context);
if (p_twai_obj->mode == TWAI_MODE_LISTEN_ONLY) {
//Error counters are frozen under listen only mode thus are meaningless. Simply return 0 in this case.
status_info->tx_error_counter = 0;
status_info->rx_error_counter = 0;
} else {
status_info->tx_error_counter = twai_hal_get_tec(&twai_context);
status_info->rx_error_counter = twai_hal_get_rec(&twai_context);
}
status_info->msgs_to_tx = p_twai_obj->tx_msg_count;
status_info->msgs_to_rx = p_twai_obj->rx_msg_count;
status_info->tx_failed_count = p_twai_obj->tx_failed_count;

15
components/hal/twai_hal.c
View File

@ -83,6 +83,21 @@ void twai_hal_configure(twai_hal_context_t *hal_ctx, const twai_timing_config_t
void twai_hal_start(twai_hal_context_t *hal_ctx, twai_mode_t mode)
{
twai_ll_set_mode(hal_ctx->dev, mode); //Set operating mode
//Clear the TEC and REC
twai_ll_set_tec(hal_ctx->dev, 0);
#ifdef CONFIG_TWAI_ERRATA_FIX_LISTEN_ONLY_DOM
/*
Errata workaround: Prevent transmission of dominant error frame while in listen only mode by setting REC to 128
before exiting reset mode. This forces the controller to be error passive (thus only transmits recessive bits).
The TEC/REC remain frozen in listen only mode thus ensuring we remain error passive.
*/
if (mode == TWAI_MODE_LISTEN_ONLY) {
twai_ll_set_rec(hal_ctx->dev, 128);
} else
#endif
{
twai_ll_set_rec(hal_ctx->dev, 0);
}
(void) twai_ll_get_and_clear_intrs(hal_ctx->dev); //Clear any latched interrupts
TWAI_HAL_SET_BITS(hal_ctx->state_flags, TWAI_HAL_STATE_FLAG_RUNNING);
twai_ll_exit_reset_mode(hal_ctx->dev);