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Improved speed of SPI::write(byte)

This commit is contained in:
Roger Clark 2015-03-06 22:40:53 +11:00
parent f21592574f
commit ac742edbd7
1 changed files with 11 additions and 1 deletions
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12
STM32F1/libraries/SPI/src/SPI.cpp
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@ -298,7 +298,17 @@ void SPIClass::read(uint8 *buf, uint32 len) {
} }
void SPIClass::write(uint8 byte) { void SPIClass::write(uint8 byte) {
this->write(&byte, 1); // this->write(&byte, 1);
/* Roger Clark
* Improved speed by just directly writing the single byte to the SPI data reg and wait for completion, * by taking the Tx code from transfer(byte)
* The original method, of calling write(*data, length) .
* This almost doubles the speed of this function.
*/
spi_tx_reg(this->spi_d, byte); // "2. Write the first data item to be transmitted into the SPI_DR register (this clears the TXE flag)."
while (spi_is_tx_empty(this->spi_d) == 0); // "5. Wait until TXE=1 ..."
while (spi_is_busy(this->spi_d) != 0); // "... and then wait until BSY=0 before disabling the SPI."
} }
void SPIClass::write(const uint8 *data, uint32 length) { void SPIClass::write(const uint8 *data, uint32 length) {