7290 I2C键盘显示C51程序（国外英文资料）.docVIP

7290 I2C键盘显示C51程序（国外英文资料） The 7290 I2C keyboard shows the C51 program [2005-8-17] , * * * * * * * * * File: iic. H Description: for 24MHz, refer to the program at Author: kassey@126.com Date: July, 7th, 2005 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * # I nclude reg5.h / * header file contains * / # I nclude intrins. H # define _Nop () _nop_ () / * define empty instruction * / / * often, variable definition area * / / * port bit definition * / Sbit SDA P1 = ^ 0; / * simulate I2C data transfer bit * / Sbit SCL P1 = ^ 1; / * simulate the I2C clock control bit * / / * status flag * / An ack bit; / * reply mark bit * / / * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Starting bus function Function prototype: void Start_I2c (); Function: start the I2C bus, which is the I2C start condition. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * / Void Start_I2c () { SDA = 1; / * sends the data signal * / _Nop (); _Nop (); SCL = 1; _Nop (); / * initial conditions are established over 4.7 us, delay times _Nop (); _Nop (); _Nop (); _Nop (); _Nop (); / * initial conditions are established over 4.7 us, delay times _Nop (); _Nop (); _Nop (); _Nop (); SDA = 0; / * send the initial signal * / _Nop (); / * the initial condition lock is greater than 4 mu s * / _Nop (); _Nop (); _Nop (); _Nop (); _Nop (); / * initial conditions are established over 4.7 us, delay times _Nop (); _Nop (); _Nop (); _Nop (); SCL = 0; / * clamp down on the I2C bus, ready to send or receive data * / _Nop (); _Nop (); _Nop (); _Nop (); } / * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * End bus function Function prototype: void Stop_I2c (); Function: end the I2C bus, which is the end of the I2C. * * * * * * * * * * * * * *