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[chore] Speedup for simple SPI.transfer #2082

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[chore] Speedup for simple SPI.transfer #2082

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d1dbc88
- major speedup for simple SPI.transfer(data) and SPI.transfer(buffer…
RudolphRiedel Jul 22, 2023
8f52dcc
- fixed indentation
RudolphRiedel Jul 24, 2023
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50 changes: 50 additions & 0 deletions libraries/SPI/src/SPI.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -398,6 +398,56 @@ void SPIClass::transfer(byte _pin, void *_bufout, void *_bufin, size_t _count, S
}
}

/**
* @brief Transfer one byte on the SPI bus.
* begin() or beginTransaction() must be called at least once before.
* @param data: byte to send.
* @return byte received from the slave.
*/
uint8_t SPIClass::transfer(uint8_t data)
{
#if defined(SPI_SR_TXP)
while (!LL_SPI_IsActiveFlag_TXP(_spi.handle.Instance));
#else
while (!LL_SPI_IsActiveFlag_TXE(_spi.handle.Instance));
#endif
LL_SPI_TransmitData8(_spi.handle.Instance, data);

#if defined(SPI_SR_RXP)
while (!LL_SPI_IsActiveFlag_RXP(_spi.handle.Instance));
#else
while (!LL_SPI_IsActiveFlag_RXNE(_spi.handle.Instance));
#endif
return LL_SPI_ReceiveData8(_spi.handle.Instance);
}

/**
* @brief Transfer several bytes. Only one buffer used to send and receive data.
* begin() or beginTransaction() must be called at least once before.
* @param buf: pointer to the bytes to send. The bytes received are copy in
* this buffer.
* @param count: number of bytes to send/receive.
*/
void SPIClass::transfer(void *buf, size_t count)
{
uint8_t *buffer = (uint8_t *) buf;
for (size_t index = 0; index < count; index++) {
#if defined(SPI_SR_TXP)
while (!LL_SPI_IsActiveFlag_TXP(_spi.handle.Instance));
#else
while (!LL_SPI_IsActiveFlag_TXE(_spi.handle.Instance));
#endif
LL_SPI_TransmitData8(_spi.handle.Instance, buffer[index]);

#if defined(SPI_SR_RXP)
while (!LL_SPI_IsActiveFlag_RXP(_spi.handle.Instance));
#else
while (!LL_SPI_IsActiveFlag_RXNE(_spi.handle.Instance));
#endif
buffer[index] = LL_SPI_ReceiveData8(_spi.handle.Instance);
}
}

/**
* @brief Not implemented.
*/
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12 changes: 3 additions & 9 deletions libraries/SPI/src/SPI.h
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
extern "C" {
#include "utility/spi_com.h"
}
#include "stm32yyxx_ll_spi.h"

// SPI_HAS_TRANSACTION means SPI has
// - beginTransaction()
Expand Down Expand Up @@ -178,21 +179,14 @@ class SPIClass {
virtual void transfer(byte _pin, void *_bufout, void *_bufin, size_t _count, SPITransferMode _mode = SPI_LAST);

// Transfer functions when user controls himself the CS pin.
byte transfer(uint8_t _data, SPITransferMode _mode = SPI_LAST)
{
return transfer(CS_PIN_CONTROLLED_BY_USER, _data, _mode);
}
virtual uint8_t transfer(uint8_t data);
virtual void transfer(void *buf, size_t count);

uint16_t transfer16(uint16_t _data, SPITransferMode _mode = SPI_LAST)
{
return transfer16(CS_PIN_CONTROLLED_BY_USER, _data, _mode);
}

void transfer(void *_buf, size_t _count, SPITransferMode _mode = SPI_LAST)
{
transfer(CS_PIN_CONTROLLED_BY_USER, _buf, _count, _mode);
}

void transfer(void *_bufout, void *_bufin, size_t _count, SPITransferMode _mode = SPI_LAST)
{
transfer(CS_PIN_CONTROLLED_BY_USER, _bufout, _bufin, _count, _mode);
Expand Down