Espressif ESP32-S2 - Page 461

Chapter 2. API Reference
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//Configure message to transmit
twai_message_t message;
message.identifier = 0xAAAA;
message.extd = 1;
message.data_length_code = 4;
for (int i = 0; i < 4; i++) {
message.data[i] = 0;
}
//Queue message for transmission
if (twai_transmit(&message, pdMS_TO_TICKS(1000)) == ESP_OK) {
printf("Message queued for transmission\n");
} else {
printf("Failed to queue message for transmission\n");
}
Message Reception The following code snippet demonstrates how to receive a message via the usage of the
twai_message_t type and twai_receive() function.
#include "driver/twai.h"
...
//Wait for message to be received
twai_message_t message;
if (twai_receive(&message, pdMS_TO_TICKS(10000)) == ESP_OK) {
printf("Message received\n");
} else {
printf("Failed to receive message\n");
return;
}
//Process received message
if (message.extd) {
printf("Message is in Extended Format\n");
} else {
printf("Message is in Standard Format\n");
}
printf("ID is %d\n", message.identifier);
if (!(message.rtr)) {
for (int i = 0; i < message.data_length_code; i++) {
printf("Data byte %d = %d\n", i, message.data[i]);
}
}
Reconfiguring and Reading Alerts The following code snippet demonstrates how to reconfigure and read TWAI
driver alerts via the use of the twai_reconfigure_alerts() and twai_read_alerts() functions.
#include "driver/twai.h"
...
//Reconfigure alerts to detect Error Passive and Bus-Off error states
uint32_t alerts_to_enable = TWAI_ALERT_ERR_PASS | TWAI_ALERT_BUS_OFF;
if (twai_reconfigure_alerts(alerts_to_enable, NULL) == ESP_OK) {
printf("Alerts reconfigured\n");
} else {
printf("Failed to reconfigure alerts");
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