我最近让 I2C 立即与一些 MCC 生成的函数一起工作，这些函数在 .h 文件中有很好的记录，但是 SPI 什么也没给我，让我感到沮丧，因为我是这些串行协议的新手，这对我没有帮助。
我只是试图读取MCP23S17上的寄存器，然后写入它，然后再次读取它以验证它是否已更改。
我什至不确定我是否以正确的方式进行此操作，但我已将我的代码包含在下面的注释中。出于某种原因，我似乎需要添加一些虚拟写入才能使第一次读取工作，但只发生在第二个循环中。
#include "mcc_generated_files/mcc.h"
uint8_t receiveData; /* Data that will be received */
uint8_t OpCodeW = 0x40;
uint8_t OpCodeR = 0x41;
void main(void)
{
SYSTEM_Initialize();
INTERRUPT_GlobalInterruptEnable();
INTERRUPT_PeripheralInterruptEnable();
Reset1_GPIO_SetLow();
__delay_ms(200);
Reset1_GPIO_SetHigh();
__delay_ms(200);
printf("Initalised \r\n");
while (1)
{
SPI1_Open(SPI1_DEFAULT);
CS1_GPIO_SetLow();
// Read IODIRA Register 0x00
SPI1_ExchangeByte(OpCodeR); // Address + Read
SPI1_ExchangeByte(0x00); // ??? -- When I add this in it works 2nd loop -- ???
receiveData = SPI1_ExchangeByte(0x00); // Returns 0x00 1st loop, then 0xFF after ...
// ... but only when duplicate sending of byte above ???
printf("Read IODIRA: 0x%02x \r\n", receiveData);
// Try writing to IODIRA Register
// Not sure what SPI1_WriteByte actually does!
// I thought it might be the same as ExchangeByte but without anything returned
// No idea!
SPI1_WriteByte(OpCodeW); // Address + Write
SPI1_WriteByte(0x00); // Register Addres IODIRA (Port A)
SPI1_WriteByte(0xF0); // Data to be written
// Read back changed IODIRA Register again - Same routine as above
SPI1_ExchangeByte(OpCodeR); // Address + Read
SPI1_ExchangeByte(0x00); // Same routine as above ...
// ... but always prints 0x00
receiveData = SPI1_ExchangeByte(0x00); // Register Address, IODIRA (Port A)
printf("Wrote to IODIRA and read back: 0x%02x \r\n", receiveData);
printf(" ----- \r\n\n");
CS1_GPIO_SetHigh();
SPI1_Close();
__delay_ms(5000);
}
}
实际的打印输出如下所示：
Initalised
Read IODIRA: 0x00 // Should be 0xFF
Wrote to IODIRA and read back: 0x00 // Should be 0xF0
-----
Read IODIRA: 0xff // This is right now!
Wrote to IODIRA and read back: 0x00 // but this hasn't changed
-----
Read IODIRA: 0xff
Wrote to IODIRA and read back: 0x00
Read IODIRA: 0xff
Wrote to IODIRA and read back: 0x00
- 我的主要问题是我以正确的方式接近这个吗？
- 为什么我需要一些虚拟写入才能让它在第二个循环上工作？- 明显错误
- SPI1_ExchangeByte 和 SPI1_WriteByte 有什么区别。
- 是否有一些文档或指南来使用我缺少的这些功能？！？！？
非常感谢任何帮助。