initial WIP

lots of code copied over, things filled in to hopefully get the LED matrix lighting up. untested.

firmware/app/comms/spi_master.c

@@ -0,0 +1,67 @@
+/*
+ * spi_master.c
+ *
+ * manage chip select externally.
+ *
+ * current version is BLOCKING. update later to use interrupt or DMA.
+ */
+
+#include "spi_master.h"
+
+
+
+void spim_init()
+{
+    SPI_InitTypeDef spi = {0};
+
+    spi.SPI_Direction   = SPI_Direction_2Lines_FullDuplex;
+    spi.SPI_Mode        = SPI_Mode_Master;
+    spi.SPI_DataSize    = SPI_DataSize_8b;
+    spi.SPI_CPOL        = SPI_CPOL_High;
+    spi.SPI_CPHA        = SPI_CPHA_2Edge;
+    spi.SPI_NSS         = SPI_NSS_Soft;
+    spi.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_2;
+    spi.SPI_FirstBit    = SPI_FirstBit_MSB;
+
+    SPI_Init(SPI1, &spi);
+
+    SPI_Cmd(SPI1, ENABLE);
+}
+
+void spim_write_raw(const uint8_t *data, uint16_t len)
+{
+    // todo: make non-blocking, timeout and error checking
+    while (len) {
+        if (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE)) {
+            SPI_I2S_SendData(SPI1, *data);
+            data++;
+            len--;
+        }
+    }
+}
+
+void spim_write_reg8(uint8_t reg, const uint8_t *data, uint16_t len)
+{
+    spim_write_raw(&reg, 1);
+    spim_write_raw(data, len);
+}
+
+void spim_read_raw(uint8_t *data, uint16_t len)
+{
+    // todo: non-blocking, timeout and error checking
+    while (len) {
+        while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_BSY)) {};
+
+        if (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE)) {
+            *data++ = SPI_I2S_ReceiveData(SPI1);
+            len--;
+        }
+        SPI_I2S_SendData(SPI1, 0);
+    }
+}
+
+void spim_read_reg8(uint8_t reg, uint8_t *data, uint16_t len)
+{
+    spim_write_raw(&reg, 1);
+    spim_read_raw(data, len);
+}