From 1611cf98dab67d90c987a261f1b804e33b94ca68 Mon Sep 17 00:00:00 2001 From: Dan Halbert Date: Fri, 18 Nov 2022 18:27:38 -0500 Subject: [PATCH] have clock start high in SPI mode 3 --- ports/raspberrypi/common-hal/busio/SPI.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/ports/raspberrypi/common-hal/busio/SPI.c b/ports/raspberrypi/common-hal/busio/SPI.c index a7b97823f9..67323790bf 100644 --- a/ports/raspberrypi/common-hal/busio/SPI.c +++ b/ports/raspberrypi/common-hal/busio/SPI.c @@ -151,6 +151,15 @@ bool common_hal_busio_spi_configure(busio_spi_obj_t *self, spi_set_format(self->peripheral, bits, polarity, phase, SPI_MSB_FIRST); + // Workaround to start with clock line high if polarity=1. The hw SPI peripheral does not do this + // automatically. See https://github.com/raspberrypi/pico-sdk/issues/868 and + // https://forums.raspberrypi.com/viewtopic.php?t=336142 + // TODO: scheduled to be be fixed in pico-sdk 1.5.0. + if (polarity) { + hw_clear_bits(&spi_get_hw(self->peripheral)->cr1, SPI_SSPCR1_SSE_BITS); // disable the SPI + hw_set_bits(&spi_get_hw(self->peripheral)->cr1, SPI_SSPCR1_SSE_BITS); // re-enable the SPI + } + self->polarity = polarity; self->phase = phase; self->bits = bits;