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Very minor SPI speedup

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This commit is contained in:
Scott Lahteine
2019-02-20 04:00:49 -06:00
parent 422dd6666e
commit 758c6c9464
3 changed files with 47 additions and 60 deletions
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49
Marlin/src/HAL/HAL_AVR/HAL_spi_AVR.cpp
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@ -27,8 +27,6 @@
/**
* Description: HAL for AVR - SPI functions
*
* For __AVR__
*/
#ifdef __AVR__
@ -68,10 +66,12 @@ void spiBegin (void) {
}
//------------------------------------------------------------------------------
#if DISABLED(SOFTWARE_SPI)
// functions for hardware SPI
//------------------------------------------------------------------------------
// Hardware SPI
//------------------------------------------------------------------------------
// make sure SPCR rate is in expected bits
#if (SPR0 != 0 || SPR1 != 1)
#error "unexpected SPCR bits"
@ -95,14 +95,13 @@ void spiBegin (void) {
SPSR = spiRate & 1 || spiRate == 6 ? 0 : _BV(SPI2X);
}
//------------------------------------------------------------------------------
/** SPI receive a byte */
uint8_t spiRec(void) {
SPDR = 0xFF;
while (!TEST(SPSR, SPIF)) { /* Intentionally left empty */ }
return SPDR;
}
//------------------------------------------------------------------------------
/** SPI read data */
void spiRead(uint8_t* buf, uint16_t nbyte) {
if (nbyte-- == 0) return;
@ -115,13 +114,13 @@ void spiBegin (void) {
while (!TEST(SPSR, SPIF)) { /* Intentionally left empty */ }
buf[nbyte] = SPDR;
}
//------------------------------------------------------------------------------
/** SPI send a byte */
void spiSend(uint8_t b) {
SPDR = b;
while (!TEST(SPSR, SPIF)) { /* Intentionally left empty */ }
}
//------------------------------------------------------------------------------
/** SPI send block */
void spiSendBlock(uint8_t token, const uint8_t* buf) {
SPDR = token;
@ -191,25 +190,21 @@ void spiBegin (void) {
}
//------------------------------------------------------------------------------
#else // SOFTWARE_SPI
//------------------------------------------------------------------------------
#else
/** nop to tune soft SPI timing */
#define nop asm volatile ("\tnop\n")
/** Set SPI rate */
void spiInit(uint8_t spiRate) {
// nothing to do
UNUSED(spiRate);
UNUSED(spiRate); // nothing to do
}
/** Begin SPI transaction, set clock, bit order, data mode */
void spiBeginTransaction(uint32_t spiClock, uint8_t bitOrder, uint8_t dataMode) {
// nothing to do
UNUSED(spiBeginTransaction);
UNUSED(spiBeginTransaction); // nothing to do
}
//------------------------------------------------------------------------------
/** Soft SPI receive byte */
uint8_t spiRec() {
uint8_t data = 0;
@ -221,8 +216,7 @@ void spiBegin (void) {
for (uint8_t i = 0; i < 8; i++) {
WRITE(SCK_PIN, HIGH);
// adjust so SCK is nice
nop;
nop; // adjust so SCK is nice
nop;
data <<= 1;
@ -231,48 +225,45 @@ void spiBegin (void) {
WRITE(SCK_PIN, LOW);
}
// enable interrupts
sei();
return data;
}
//------------------------------------------------------------------------------
/** Soft SPI read data */
void spiRead(uint8_t* buf, uint16_t nbyte) {
for (uint16_t i = 0; i < nbyte; i++)
buf[i] = spiRec();
}
//------------------------------------------------------------------------------
/** Soft SPI send byte */
void spiSend(uint8_t data) {
// no interrupts during byte send - about 8µs
cli();
for (uint8_t i = 0; i < 8; i++) {
WRITE(SCK_PIN, LOW);
WRITE(MOSI_PIN, data & 0x80);
data <<= 1;
WRITE(SCK_PIN, HIGH);
}
// hold SCK high for a few ns
nop;
nop; // hold SCK high for a few ns
nop;
nop;
nop;
WRITE(SCK_PIN, LOW);
// enable interrupts
sei();
}
//------------------------------------------------------------------------------
/** Soft SPI send block */
void spiSendBlock(uint8_t token, const uint8_t* buf) {
spiSend(token);
for (uint16_t i = 0; i < 512; i++)
spiSend(buf[i]);
}
#endif // SOFTWARE_SPI
#endif // SOFTWARE_SPI
#endif // __AVR__