Date:2012-06-23 19:54:31 (11 years 9 months ago)
Author:Werner Almesberger
Commit:dd72f4642e6708ec90bbfacfe23dd2dd5cfd172b
Message:fw/spi.c: explain why we probably can't reach fosc/2 = 4 MHz

Files: fw/spi.c (1 diff)

Change Details

fw/spi.c
2424#define SCLK B, 8
2525
2626
27/*
28 * According to simulation, signals from MCU to transceiver should already
29 * suffer severe degradation * at fosc/4 = 2 MHz due to parasitic capacitance
30 * (assumed to be 10 pF) and the series resistors (10 kOhm) of the voltage
31 * dividers.
32 *
33 * fosc/2 = 4 MHz looks horrible in simulation and does not work reliably in
34 * practice either.
35 */
36
2737void spi_init(void)
2838{
2939    /* SPI mode 0, MSB first, fosc/4 */

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