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spi: Add SPI transfer function that pass in RX/TX

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When using SPI, I prefer to not have to do malloc/free functions for each
transfer, so why not have a transfer function that you can pass in both
buffers.  With my ILI9341 TFT display code that gave some perf wins, also more
of a win, you can pass in NULL for recv buffer and the underlying device driver
does not have to copy the data.

Signed-off-by: Kurt Eckhardt <kurte@rockisland.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>
This commit is contained in:
Kurt Eckhardt
2014-10-18 09:25:19 -07:00
committed by Brendan Le Foll
parent 54deb01796
commit 2a11e31052
4 changed files with 53 additions and 5 deletions
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13
examples/c++/Spi-pot.cpp
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@@ -49,6 +49,7 @@ int main ()
spi = new mraa::Spi(0);
char data[] = {0x00, 100};
char rxBuf[2];
char *recv;
while (running == 0) {
int i;
@@ -56,14 +57,18 @@ int main ()
data[1] = i;
recv = spi->write(data, 2);
printf("Writing -%i",i);
printf("RECIVED-%i-%i\n",recv[0],recv[1]);
if (recv) {
printf("RECIVED-%i-%i\n",recv[0],recv[1]);
free(recv);
}
usleep(100000);
}
for (i = 130; i > 90; i--) {
data[1] = i;
recv = spi->write(data, 2);
printf("Writing -%i",i);
printf("RECIVED-%i-%i\n",recv[0],recv[1]);
if (spi->transfer(data, rxBuf, 2) == MRAA_SUCCESS) {
printf("Writing -%i",i);
printf("RECIVED-%i-%i\n",rxBuf[0],rxBuf[1]);
}
usleep(100000);
}