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esp32/machine_hw_spi: Fix large HW SPI transfers by splitting them up.

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Breaks up HW SPI transfers into maximum chunks of 32736 bits (4092 bytes),
because this is the maximum that the underlying ESP IDF will accept.
This commit is contained in:
Eric Poulsen 2017-11-28 18:48:30 -08:00 committed by Damien George
parent 5455bf79c5
commit 9123c8d946
1 changed files with 37 additions and 17 deletions
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50
ports/esp32/machine_hw_spi.c
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@ -36,6 +36,9 @@
#include "driver/spi_master.h"
#define MP_HW_SPI_MAX_XFER_BYTES (4092)
#define MP_HW_SPI_MAX_XFER_BITS (MP_HW_SPI_MAX_XFER_BYTES * 8) // Has to be an even multiple of 8
typedef struct _machine_hw_spi_obj_t {
mp_obj_base_t base;
spi_host_device_t host;
@ -227,35 +230,52 @@ STATIC void machine_hw_spi_deinit(mp_obj_base_t *self_in) {
STATIC void machine_hw_spi_transfer(mp_obj_base_t *self_in, size_t len, const uint8_t *src, uint8_t *dest) {
machine_hw_spi_obj_t *self = MP_OBJ_TO_PTR(self_in);
int bits_to_send = len * self->bits;
bool shortMsg = len <= 4;
if (self->state == MACHINE_HW_SPI_STATE_DEINIT) {
mp_raise_msg(&mp_type_OSError, "transfer on deinitialized SPI");
return;
}
struct spi_transaction_t transaction = {
.flags = 0,
.length = bits_to_send,
.tx_buffer = NULL,
.rx_buffer = NULL,
};
struct spi_transaction_t transaction = { 0 };
if (shortMsg) {
// Round to nearest whole set of bits
int bits_to_send = len * 8 / self->bits * self->bits;
if (len <= 4) {
if (src != NULL) {
memcpy(&transaction.tx_data, src, len);
}
transaction.flags |= (SPI_TRANS_USE_TXDATA | SPI_TRANS_USE_RXDATA);
transaction.flags = SPI_TRANS_USE_TXDATA | SPI_TRANS_USE_RXDATA;
transaction.length = bits_to_send;
spi_device_transmit(self->spi, &transaction);
if (dest != NULL) {
memcpy(dest, &transaction.rx_data, len);
}
} else {
transaction.tx_buffer = src;
transaction.rx_buffer = dest;
int offset = 0;
int bits_remaining = bits_to_send;
while (bits_remaining) {
memset(&transaction, 0, sizeof(transaction));
transaction.length =
bits_remaining > MP_HW_SPI_MAX_XFER_BITS ? MP_HW_SPI_MAX_XFER_BITS : bits_remaining;
if (src != NULL) {
transaction.tx_buffer = src + offset;
}
if (dest != NULL) {
transaction.rx_buffer = dest + offset;
}
spi_device_transmit(self->spi, &transaction);
bits_remaining -= transaction.length;
if (shortMsg && dest != NULL) {
memcpy(dest, &transaction.rx_data, len);
// doesn't need ceil(); loop ends when bits_remaining is 0
offset += transaction.length / 8;
}
}
}