Initial Release

pio/spi/spi_flash.c

@@ -0,0 +1,155 @@
+/**
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdio.h>
+
+#include "pico/stdlib.h"
+#include "pio_spi.h"
+
+// This example uses PIO to erase, program and read back a SPI serial flash
+// memory.
+
+#define PIN_MISO 16
+#define PIN_MOSI 17
+#define PIN_SCK 18
+#define PIN_CS 19
+
+// ----------------------------------------------------------------------------
+// Generic serial flash code
+
+#define FLASH_PAGE_SIZE        256
+#define FLASH_SECTOR_SIZE      4096
+
+#define FLASH_CMD_PAGE_PROGRAM 0x02
+#define FLASH_CMD_READ         0x03
+#define FLASH_CMD_STATUS       0x05
+#define FLASH_CMD_WRITE_EN     0x06
+#define FLASH_CMD_SECTOR_ERASE 0x20
+
+#define FLASH_STATUS_BUSY_MASK 0x01
+
+void flash_read(const pio_spi_inst_t *spi, uint32_t addr, uint8_t *buf, size_t len) {
+    uint8_t cmd[4] = {
+            FLASH_CMD_READ,
+            addr >> 16,
+            addr >> 8,
+            addr
+    };
+    gpio_put(spi->cs_pin, 0);
+    pio_spi_write8_blocking(spi, cmd, 4);
+    pio_spi_read8_blocking(spi, buf, len);
+    gpio_put(spi->cs_pin, 1);
+}
+
+
+void flash_write_enable(const pio_spi_inst_t *spi) {
+    uint8_t cmd = FLASH_CMD_WRITE_EN;
+    gpio_put(spi->cs_pin, 0);
+    pio_spi_write8_blocking(spi, &cmd, 1);
+    gpio_put(spi->cs_pin, 1);
+}
+
+void flash_wait_done(const pio_spi_inst_t *spi) {
+    uint8_t status;
+    do {
+        gpio_put(spi->cs_pin, 0);
+        uint8_t cmd = FLASH_CMD_STATUS;
+        pio_spi_write8_blocking(spi, &cmd, 1);
+        pio_spi_read8_blocking(spi, &status, 1);
+        gpio_put(spi->cs_pin, 1);
+    } while (status & FLASH_STATUS_BUSY_MASK);
+}
+
+void flash_sector_erase(const pio_spi_inst_t *spi, uint32_t addr) {
+    uint8_t cmd[4] = {
+            FLASH_CMD_SECTOR_ERASE,
+            addr >> 16,
+            addr >> 8,
+            addr
+    };
+    flash_write_enable(spi);
+    gpio_put(spi->cs_pin, 0);
+    pio_spi_write8_blocking(spi, cmd, 4);
+    gpio_put(spi->cs_pin, 1);
+    flash_wait_done(spi);
+}
+
+void flash_page_program(const pio_spi_inst_t *spi, uint32_t addr, uint8_t data[]) {
+    flash_write_enable(spi);
+    uint8_t cmd[4] = {
+            FLASH_CMD_PAGE_PROGRAM,
+            addr >> 16,
+            addr >> 8,
+            addr
+    };
+    gpio_put(spi->cs_pin, 0);
+    pio_spi_write8_blocking(spi, cmd, 4);
+    pio_spi_write8_blocking(spi, data, FLASH_PAGE_SIZE);
+    gpio_put(spi->cs_pin, 1);
+    flash_wait_done(spi);
+}
+
+// ----------------------------------------------------------------------------
+// Example program
+
+void printbuf(const uint8_t buf[FLASH_PAGE_SIZE]) {
+    for (int i = 0; i < FLASH_PAGE_SIZE; ++i)
+        printf("%02x%c", buf[i], i % 16 == 15 ? '\n' : ' ');
+}
+
+int main() {
+    stdio_init_all();
+    puts("PIO SPI Example");
+
+    pio_spi_inst_t spi = {
+            .pio = pio0,
+            .sm = 0,
+            .cs_pin = PIN_CS
+    };
+
+    gpio_init(PIN_CS);
+    gpio_put(PIN_CS, 1);
+    gpio_set_dir(PIN_CS, GPIO_OUT);
+
+    uint offset = pio_add_program(spi.pio, &spi_cpha0_program);
+    printf("Loaded program at %d\n", offset);
+
+    pio_spi_init(spi.pio, spi.sm, offset,
+                 8,       // 8 bits per SPI frame
+                 31.25f,  // 1 MHz @ 125 clk_sys
+                 false,   // CPHA = 0
+                 false,   // CPOL = 0
+                 PIN_SCK,
+                 PIN_MOSI,
+                 PIN_MISO
+    );
+
+    uint8_t page_buf[FLASH_PAGE_SIZE];
+
+    const uint32_t target_addr = 0;
+
+    flash_sector_erase(&spi, target_addr);
+    flash_read(&spi, target_addr, page_buf, FLASH_PAGE_SIZE);
+
+    puts("After erase:");
+    printbuf(page_buf);
+
+    for (int i = 0; i < FLASH_PAGE_SIZE; ++i)
+        page_buf[i] = i;
+    flash_page_program(&spi, target_addr, page_buf);
+    flash_read(&spi, target_addr, page_buf, FLASH_PAGE_SIZE);
+
+    puts("After program:");
+    printbuf(page_buf);
+
+    flash_sector_erase(&spi, target_addr);
+    flash_read(&spi, target_addr, page_buf, FLASH_PAGE_SIZE);
+
+    puts("Erase again:");
+    printbuf(page_buf);
+
+    return 0;
+}