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Quotation

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注册时间： 2018-10-04

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SPI Flash不能写入问题解决

F1C100s，XBoot下调用block和spi-flash驱动操作SPI Flash，能读，不能擦除不能写。

断断续续调了几天终于调通了，问题出在Flash CS时序。XBoot spi-flash驱动里的CS时序不满足我用的Flash的要求。
我用的Puya普冉的Flash（很便宜），数据手册里特意说了，某些操作必须在字节边界处置CS为高，这是出于数据保护的目的，检查命令长度，如果长度错了就不执行命令。

For the following instructions: WREN, WRDI, WRSR, PE, SE, BE32K, BE, CE, PP, DPP, QPP, DP, ERSCUR, PRSCUR, SUSPEND, RESUME, RSTEN, RST, the CS# must go high exactly at the byte boundary; otherwise, the instruction will be rejected and not executed.

也就是说SPI在发送完这几个命令和数据后，需要马上拉高CS。但XBoot里的Flash驱动是按照别的Flash写的，时序不满足这个要求。因此在spi-flash.c加入一些spi_device_select()和spi_device_deselect()，就能够擦除写入了！代码改动如下。

static void spi_flash_sector_erase(struct spi_device_t * dev, u64_t addr)
{
	u8_t tx[4];

	spi_device_select(dev);
	spi_flash_write_enable(dev);
	spi_device_deselect(dev);

	tx[0] = OPCODE_SE;
	tx[1] = (u8_t)(addr >> 16);
	tx[2] = (u8_t)(addr >> 8);
	tx[3] = (u8_t)(addr >> 0);
	spi_device_select(dev);
	spi_device_write_then_read(dev, tx, 4, 0, 0);
	spi_device_deselect(dev);

	spi_device_select(dev);
	spi_flash_wait_for_busy(dev);
	spi_device_deselect(dev);
}

static void spi_flash_sector_erase_4k(struct spi_device_t * dev, u64_t addr)
{
	u8_t tx[4];

	spi_device_select(dev);
	spi_flash_write_enable(dev);
	spi_device_deselect(dev);

	tx[0] = OPCODE_BE_4K;
	tx[1] = (u8_t)(addr >> 16);
	tx[2] = (u8_t)(addr >> 8);
	tx[3] = (u8_t)(addr >> 0);
	spi_device_select(dev);
	spi_device_write_then_read(dev, tx, 4, 0, 0);
	spi_device_deselect(dev);

	spi_device_select(dev);
	spi_flash_wait_for_busy(dev);
	spi_device_deselect(dev);
}

static void spi_flash_write_one_page(struct spi_device_t * dev, u64_t addr, u8_t * buf)
{
	u8_t tx[4];

	spi_device_select(dev);
	spi_flash_write_enable(dev);
	spi_device_deselect(dev);

	tx[0] = OPCODE_PP;
	tx[1] = (u8_t)(addr >> 16);
	tx[2] = (u8_t)(addr >> 8);
	tx[3] = (u8_t)(addr >> 0);
	spi_device_select(dev);
	spi_device_write_then_read(dev, tx, 4, 0, 0);
	spi_device_write_then_read(dev, buf, 256, 0, 0);
	spi_device_deselect(dev);

	spi_device_select(dev);
	spi_flash_wait_for_busy(dev);
	spi_device_deselect(dev);
}

按理说，可以用SPI硬件自动控制CS。sunxi-tools里就是这样做的，没有操作CS的代码，也能正确写入。但我还没调出来，目前仍然用软件控制CS。

最近编辑记录 Quotation (2019-01-30 11:09:54)