Initial Release

2021-01-20 10:49:34 -06:00
commit 46078742c7
245 changed files with 21157 additions and 0 deletions
--- a/pio/spi/spi_loopback.c
+++ b/pio/spi/spi_loopback.c
@@ -0,0 +1,77 @@
+/**
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "pico/stdlib.h"
+#include "pio_spi.h"
+
+// This program instantiates a PIO SPI with each of the four possible
+// CPOL/CPHA combinations, with the serial input and output pin mapped to the
+// same GPIO. Any data written into the state machine's TX FIFO should then be
+// serialised, deserialised, and reappear in the state machine's RX FIFO.
+
+#define PIN_SCK 18
+#define PIN_MOSI 16
+#define PIN_MISO 16 // same as MOSI, so we get loopback
+
+#define BUF_SIZE 20
+
+void test(const pio_spi_inst_t *spi) {
+    static uint8_t txbuf[BUF_SIZE];
+    static uint8_t rxbuf[BUF_SIZE];
+    printf("TX:");
+    for (int i = 0; i < BUF_SIZE; ++i) {
+        txbuf[i] = rand() >> 16;
+        rxbuf[i] = 0;
+        printf(" %02x", (int) txbuf[i]);
+    }
+    printf("\n");
+
+    pio_spi_write8_read8_blocking(spi, txbuf, rxbuf, BUF_SIZE);
+
+    printf("RX:");
+    bool mismatch = false;
+    for (int i = 0; i < BUF_SIZE; ++i) {
+        printf(" %02x", (int) rxbuf[i]);
+        mismatch = mismatch || rxbuf[i] != txbuf[i];
+    }
+    if (mismatch)
+        printf("\nNope\n");
+    else
+        printf("\nOK\n");
+}
+
+int main() {
+    stdio_init_all();
+
+    pio_spi_inst_t spi = {
+            .pio = pio0,
+            .sm = 0
+    };
+    float clkdiv = 31.25f;  // 1 MHz @ 125 clk_sys
+    uint cpha0_prog_offs = pio_add_program(spi.pio, &spi_cpha0_program);
+    uint cpha1_prog_offs = pio_add_program(spi.pio, &spi_cpha1_program);
+
+    for (int cpha = 0; cpha <= 1; ++cpha) {
+        for (int cpol = 0; cpol <= 1; ++cpol) {
+            printf("CPHA = %d, CPOL = %d\n", cpha, cpol);
+            pio_spi_init(spi.pio, spi.sm,
+                         cpha ? cpha1_prog_offs : cpha0_prog_offs,
+                         8,       // 8 bits per SPI frame
+                         clkdiv,
+                         cpha,
+                         cpol,
+                         PIN_SCK,
+                         PIN_MOSI,
+                         PIN_MISO
+            );
+            test(&spi);
+            sleep_ms(10);
+        }
+    }
+}