esp-idf/components/hal/twai_hal.c
Darian Leung 3318fac02f twai: Add errata workaround for listen only mode
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
2023-02-24 19:26:22 +08:00

93 lines
3.7 KiB
C

/*
* SPDX-FileCopyrightText: 2015-2023 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <stddef.h>
#include "sdkconfig.h"
#include "hal/twai_hal.h"
#include "soc/soc_caps.h"
//Default values written to various registers on initialization
#define TWAI_HAL_INIT_TEC 0
#define TWAI_HAL_INIT_REC 0
#define TWAI_HAL_INIT_EWL 96
/* ---------------------------- Init and Config ----------------------------- */
bool twai_hal_init(twai_hal_context_t *hal_ctx)
{
//Initialize HAL context
hal_ctx->dev = &TWAI;
hal_ctx->state_flags = 0;
//Initialize TWAI controller, and set default values to registers
twai_ll_enter_reset_mode(hal_ctx->dev);
if (!twai_ll_is_in_reset_mode(hal_ctx->dev)) { //Must enter reset mode to write to config registers
return false;
}
#if SOC_TWAI_SUPPORT_MULTI_ADDRESS_LAYOUT
twai_ll_enable_extended_reg_layout(hal_ctx->dev); //Changes the address layout of the registers
#endif
twai_ll_set_mode(hal_ctx->dev, TWAI_MODE_LISTEN_ONLY); //Freeze REC by changing to LOM mode
//Both TEC and REC should start at 0
twai_ll_set_tec(hal_ctx->dev, TWAI_HAL_INIT_TEC);
twai_ll_set_rec(hal_ctx->dev, TWAI_HAL_INIT_REC);
twai_ll_set_err_warn_lim(hal_ctx->dev, TWAI_HAL_INIT_EWL); //Set default value of for EWL
return true;
}
void twai_hal_deinit(twai_hal_context_t *hal_ctx)
{
//Clear any pending registers
(void) twai_ll_get_and_clear_intrs(hal_ctx->dev);
twai_ll_set_enabled_intrs(hal_ctx->dev, 0);
twai_ll_clear_arb_lost_cap(hal_ctx->dev);
twai_ll_clear_err_code_cap(hal_ctx->dev);
hal_ctx->dev = NULL;
}
void twai_hal_configure(twai_hal_context_t *hal_ctx, const twai_timing_config_t *t_config, const twai_filter_config_t *f_config, uint32_t intr_mask, uint32_t clkout_divider)
{
//Configure bus timing, acceptance filter, CLKOUT, and interrupts
twai_ll_set_bus_timing(hal_ctx->dev, t_config->brp, t_config->sjw, t_config->tseg_1, t_config->tseg_2, t_config->triple_sampling);
twai_ll_set_acc_filter(hal_ctx->dev, f_config->acceptance_code, f_config->acceptance_mask, f_config->single_filter);
twai_ll_set_clkout(hal_ctx->dev, clkout_divider);
twai_ll_set_enabled_intrs(hal_ctx->dev, intr_mask);
(void) twai_ll_get_and_clear_intrs(hal_ctx->dev); //Clear any latched interrupts
}
/* -------------------------------- Actions --------------------------------- */
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);
}
void twai_hal_stop(twai_hal_context_t *hal_ctx)
{
twai_ll_enter_reset_mode(hal_ctx->dev);
(void) twai_ll_get_and_clear_intrs(hal_ctx->dev);
twai_ll_set_mode(hal_ctx->dev, TWAI_MODE_LISTEN_ONLY); //Freeze REC by changing to LOM mode
//Any TX is immediately halted on entering reset mode
TWAI_HAL_CLEAR_BITS(hal_ctx->state_flags, TWAI_HAL_STATE_FLAG_TX_BUFF_OCCUPIED | TWAI_HAL_STATE_FLAG_RUNNING);
}