On the NRF52840 dongle am building a protocol on USB CDC ACM.
Using app_usbd_cdc_acm_read to read one byte at a time works perfectly.
However, I can seem to make app_usbd_cdc_acm_read_any work.
Pseudo-code for app_usbd_cdc_acm_read:
static uint8_t one_byte;
static void on_byte_read() {
// TODO: Process that one_byte
}
static void usb_serial_process_read() {
for (;;) {
ret_code_t ret = app_usbd_cdc_acm_read(&m_app_cdc_acm_data,
&one_byte,
1);
if (ret == NRF_SUCCESS) {
on_byte_read();
} else if (ret == NRF_ERROR_IO_PENDING) {
break;
} else {
// TODO: Handle USB rx error
break;
}
}
}
static void cdc_acm_data_ev_handler(app_usbd_class_inst_t const * p_inst,
app_usbd_cdc_acm_user_event_t event) {
switch (event)
{
case APP_USBD_CDC_ACM_USER_EVT_PORT_OPEN:
{
usb_serial_process_read();
break;
}
case APP_USBD_CDC_ACM_USER_EVT_PORT_CLOSE:
// TODO
break;
case APP_USBD_CDC_ACM_USER_EVT_RX_DONE:
{
on_byte_read(); // one_byte is already read
usb_serial_process_read();
}
break;
case APP_USBD_CDC_ACM_USER_EVT_TX_DONE:
// TODO: handle TX
break;
default:
break;
}
}
However, using app_usbd_cdc_acm_read_any always failed to receive.
#define BUF_LEN 16
uint8_t buffer[BUF_LEN];
static void on_incoming(size_t len) {
// TODO: Process buffer and len
}
static void usb_serial_process_read(size_t total) {
for (;;) {
ret_code_t ret = app_usbd_cdc_acm_read_any(&m_app_cdc_acm_data,
buffer,
BUF_LEN);
if (ret == NRF_SUCCESS) {
size_t size = app_usbd_cdc_acm_rx_size(&m_app_cdc_acm_data);
on_incoming(size);
} else if (ret == NRF_ERROR_IO_PENDING) {
break;
} else {
// TODO: Error handling
break;
}
}
}
static void cdc_acm_data_ev_handler(app_usbd_class_inst_t const * p_inst,
app_usbd_cdc_acm_user_event_t event) {
switch (event)
{
case APP_USBD_CDC_ACM_USER_EVT_PORT_OPEN:
{
usb_serial_process_read();
break;
}
case APP_USBD_CDC_ACM_USER_EVT_PORT_CLOSE:
break;
case APP_USBD_CDC_ACM_USER_EVT_RX_DONE:
{
size_t size = app_usbd_cdc_acm_rx_size(&m_app_cdc_acm_data);
on_incoming(size);
usb_serial_process_read();
}
break;
case APP_USBD_CDC_ACM_USER_EVT_TX_DONE:
// TODO: Handle TX
break;
default:
break;
}
}
What am I missing?
