以下是 SD NAND 卡 SPI 接口的完整电路设计方案,包含核心连接、信号处理及典型应用配置:
+------+ | | | MCU | | | +------+ | | | | +----------------+--+----------------+ | | | +---+----+ +---+----+ +-----+-----+ | | | | | | | 4.7KΩ | | 4.7KΩ | | SD NAND | | 上拉 | | 上拉 | | 芯片 | | | | | | | +---+----+ +---+----+ +-----+-----+ | | | | | | +---+----+ +---+----+ +-----+-----+ | | | | | | | MCU | | MCU | | SD NAND | | CS +-------+ CS | | CS + | | | | | | | SCLK +-------+ SCLK | | SCLK + | | | | | | | MOSI +-------+ DATA | | DATA + | | | | | | | MISO +-------+ CMD | | CMD + | | | | | | +--------+ +--------+ +-----------+
关键连接说明:
+-----+ | | | VCC +----+ | | | +-----+ | +--------+ +-----+ +----| LDO |----|10μF |--+-- VDD_SD (3.3V) | |AMS1117 | +-----+ | +-----+ | +--------+ | | | | | | VIN +----+ | | | | +-----+ | +-----+ |100nF| +-----+ | GND +-----+ | | | CS +----+ | | | +-----+ | +--------+ +----| TVS |----+ | | SMBJ5.0| | +-----+ | +--------+ | | | | | | SCLK+----+ | | | | | +-----+ | | | | +-----+ | | | | | | | MOSI+----+ | | | | | +-----+ | | | | +-----+ | | | | | | | MISO+----+ | | | | | +-----+ | | | | +------------------+ | GND
电源与保护设计要点:
// SPI初始化函数void spi_init(void) { // 配置SPI控制器:模式0(CPOL=0, CPHA=0),初始速率400kHz SPI->CR1 = SPI_CR1_SPE | SPI_CR1_MSTR | SPI_CR1_BR_2; // 400kHz // 初始化CS引脚为输出,默认高电平 GPIO_SetPinMode(CS_PIN, OUTPUT); GPIO_WritePin(CS_PIN, HIGH);}// 发送命令并接收响应uint8_t spi_send_command(uint8_t cmd, uint32_t arg) { uint8_t response; // 拉低CS,选中SD NAND GPIO_WritePin(CS_PIN, LOW); // 发送命令字节(最高位为0,表示命令) spi_transfer(cmd | 0x40); // 发送32位参数 spi_transfer((arg >> 24) & 0xFF); spi_transfer((arg >> 16) & 0xFF); spi_transfer((arg >> 8) & 0xFF); spi_transfer(arg & 0xFF); // 发送CRC校验(简化,实际需计算) spi_transfer(0x95); // CMD0的CRC // 等待响应(R1格式) do { response = spi_transfer(0xFF); } while (response == 0xFF); // 释放CS GPIO_WritePin(CS_PIN, HIGH); return response;}// 读取数据块bool spi_read_block(uint32_t address, uint8_t *buffer, uint16_t length) { uint8_t response; // 发送读单块命令(CMD17) response = spi_send_command(17, address); if (response != 0x00) return false; // 等待数据令牌(0xFE) do { response = spi_transfer(0xFF); } while (response != 0xFE); // 读取数据 for (uint16_t i = 0; i < length; i++) { buffer[i] = spi_transfer(0xFF); } // 读取CRC(忽略) spi_transfer(0xFF); spi_transfer(0xFF); return true;}
通过以上电路设计和配置,可实现稳定可靠的 SD NAND SPI 接口通信。实际应用中需根据具体 SD NAND 型号的 datasheet 调整参数。
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