回复第 2 楼 香水城于2010-05-06 03:24:50发表: STM8S103F3的PB.4/PB.5可以当普通Open Drain端口使用。 PB.5做软件I2C SDA时，要读入时需要先输出"1"，然后直接读这个端口即可。 感謝您指教! 請問 是說什麼要設為1呢? 是指 GPIO->ODR 或 GPIO->DDR bit 5 要設為1呢? 依據RM0016 Page 100, CMOS SCHMITT TRIGGER 要GPIOB->DDR 為0 且ADC-TDR 為1 才致能,也才可以讀取Pin 是吧? 所以將讀取SDA 程式改寫為: bool I2C_GetSDA (void) { u8 bSDA; // Init Port B /* [2]101 7 6 5 4 3 2 1 0 | | | | | | | | | | | |_________ I2C SCL (Output) Open drain output | | |___________ I2C SDA (Input) Floating without interrupt DDR 0 0 0 1 0 0 0 0 CR1 0 0 0 0 0 0 0 0 CR2 0 0 0 0 0 0 0 0 */ GPIOB->DDR = 0x10; //GPIOB->CR1 = 0x00; //GPIOB->CR2 = 0x00; bSDA = GPIOB->IDR & 0x20; // Init Port B /* [2]101 7 6 5 4 3 2 1 0 | | | | | | | | | | | |_________ I2C SCL (Output) Open drain output | | |___________ I2C SDA (Output) Open drain output DDR 0 0 1 1 0 0 0 0 CR1 0 0 0 0 0 0 0 0 CR2 0 0 0 0 0 0 0 0 */ GPIOB->DDR = 0x30; //GPIOB->CR1 = 0x00; //GPIOB->CR2 = 0x00; return( bSDA ); } /* I2C_GetSDA */ 這樣子對嗎? 我還遺漏什麼沒注意呢?
依據RM0016 page 91: Level 0 can not be programmed (I1_x=1, I0_x=0). In this case, the previously stored value is kept. For example: if previous value is CFh, and programmed value equals 64h, the result is 44h. 這表示什麼意思呢? 是否我將 TIM4 interrupt priority 設為Level 1 即可 ? 因原本所有interrupt priority均為 Level 3. 調降TIM4 interrupt priority 即可. //ITC->ISPR2 = 0xCF; // EXTI PortD (INT06)= Level 2 (00) ITC->ISPR6 = 0x7F; // TIM4 (INT23) = Level 1 (01)
