altos: Crank down STM SPI speed for MM

The cc1120 is noisy enough to break SPI data transfers at 4MHz, so
crank things down to 1MHz. It's "stable" now, but clearly needs a
filter and shorter traces.

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/src/stm/ao_spi_stm.c b/src/stm/ao_spi_stm.c
index 8784d98564feeb5f45e914ed014d8e3824a7269a..d337864816392b04a2f5507a56dcf20bfbeea271 100644 (file)
--- a/src/stm/ao_spi_stm.c
+++ b/src/stm/ao_spi_stm.c
@@ -282,7 +282,7 @@ ao_spi_get(uint8_t spi_index)
                        (1 << STM_SPI_CR1_SSI) |                        /*  ... */
                        (0 << STM_SPI_CR1_LSBFIRST) |                   /* Big endian */
                        (1 << STM_SPI_CR1_SPE) |                        /* Enable SPI unit */
-                       (STM_SPI_CR1_BR_PCLK_8 << STM_SPI_CR1_BR) |     /* baud rate to pclk/4 */
+                       (STM_SPI_CR1_BR_PCLK_16 << STM_SPI_CR1_BR) |    /* baud rate to pclk/4 */
                        (1 << STM_SPI_CR1_MSTR) |
                        (0 << STM_SPI_CR1_CPOL) |                       /* Format 0 */
                        (0 << STM_SPI_CR1_CPHA));