模拟串口通讯，用于I0口不足是可扩展通讯-Simulation of serial communication, for mouth I0 is the lack of scalable communications

STC89C51RD单片机普通模拟IO串口-Generic software uart written in C, requiring a timer set to 3 times the baud rate, and two software read/write pins for the receive and transmit functions

使用单片机STC89C51RC普通IO口模拟串口三种方法-// 1. get_rx_pin_status() // Returns 0 or 1 dependent on whether the receive pin is high or low. // 2. set_tx_pin_high() // Sets the transmit pin to the high state. // 3. set_tx_pin_low() // Sets the transmit pi