Posted on December 11, 2015 at 12:32
First, it is very easy to make software SPI, with any data size you want. And in some times it can be as fast as your hardware SPI, if you don't use any DMA or something like that.
Second, some MCU's can use 9b data size, so so you will have to call two times to get 18 edges ( like STM32F3 , STM32F7 does have variable length of SPI 4 to 16b)
SSI its simply to avoid SPI name due to trademark i guess ( Like SMB, SPORT and so on)
This is software SPI, works for me, when i have multiple devices with different data and command size :
uint8_t sFLASH_SendByte(uint8_t byte)
{
uint8_t data = 0;
register uint16_t i = 0;
register uint32_t delay = 0x1;
data = 0;
while(i<
8
)
{
GPIO_ResetBits(GPIOB, GPIO_Pin_3);
if(((byte<<i)&0x80)==0x80)
GPIO_SetBits(GPIOB, GPIO_Pin_5);
else
GPIO_ResetBits(GPIOB, GPIO_Pin_5);
Delay(delay);
GPIO_SetBits(GPIOB, GPIO_Pin_3);
Delay(delay);
if((GPIOB->IDR & GPIO_Pin_4)==GPIO_Pin_4)
data+=0x80>>i;
GPIO_ResetBits(GPIOB, GPIO_Pin_3);
i++;
}
return data;
}
