Get ASCLL Data from PS-2 KeYboards

摘要

The PS-2 keyboard engineers assigned a unique code to each key. So, for example, the W key produces 0x1 D and the X key produces 0x22 (all values given in hexadecimal). These codes don't directly translate into ASCII values; 0x57 and 0x58, respectively. A PS-2 keyboard does, however, transmit key codes in a UART-type format: a start bit; eight data bits; an odd-parity bit; and a stop bit (Figure 1). The least- significant bit (LSB) of a key code gets shifted out first.