The 87LPC76X Microcontroller combines in a small package thebenefits of a high-performance microcontroller with on-boardhardware supporting the Inter-Integrated Circuit (I2C) bus interface.The 87LPC76X can be programmed both as an I2C bus master, aslave, or both. An overview of the I2C bus and description of the bussupport hardware in the 87LPC76X microcontrollers appears inapplication note AN464, Using the 87LPC76X Microcontroller as anI2C Bus Master. That application note includes a programmingexample, demonstrating a bus-master code. Here we show anexample of programming the microcontroller as an I2C slave.The code listing demonstrates communications routines for the87LPC76X as a slave on the I2C bus. It compliments the program inAN464 which demonstrates the 87LPC76X as an I2C bus master.One may demonstrate two 87LPC76X devices communicating witheach other on the I2C bus, using the AN464 code in one, and theprogram presented here in the other. The examples presented hereand in AN464 allow the 87LPC76X to be either a master or a slave,but not both. Switching between master and slave roles in amultimaster environment is described in application note AN435.The software for a slave on the bus is relatively simple, as theprocessor plays a relatively passive role. It does not initiate bustransfers on its own, but responds to a master initiating thecommunications. This is true whether the slave receives or transmitsdata—transmission takes place only as a response to a busmaster’s request. The slave does not have to worry about arbitrationor about devices which do not acknowledge their address. As theslave is not supposed to take control of the bus, we do not demandit to resolve bus exceptions or “hangups”. If the bus becomesinactive the processor simply withdraws, not interfering with themaster (or masters) on the bus which should (hopefully) try toresolve the situation.
標簽：
routines
slave
I2C
87L
上傳時間：
2013-11-19
上傳用戶：shirleyYim
16 16點陣顯示漢字原理及顯示程序
#include "config.h"
#define DOTLED_LINE_PORT PORTB #define DOTLED_LINE_DDR DDRB #define DOTLED_LINE_PIN PINB
#define DOTLED_LINE_SCKT PB1 #define DOTLED_LINE_SCKH PB5 #define DOTLED_LINE_SDA PB3
#define DOTLED_ROW_PORT PORTC #define DOTLED_ROW_DDR DDRC #define DOTLED_ROW_PIN PINC
#define DOTLED_ROW_A0 PC0 #define DOTLED_ROW_A1 PC1 #define DOTLED_ROW_A2 PC2 #define DOTLED_ROW_A3 PC3 #define DOTLED_ROW_E PC4 uint8 font[] = { /*-- 調入了一幅圖像：這是您新建的圖像 --*/ /*-- 寬度x高度=16x16 --*/ 0x00,0x00,0x00,0x00,0x08,0x38,0x18,0x44,0x08,0x44,0x08,0x04,0x08,0x08,0x08,0x10, 0x08,0x20,0x08,0x40,0x08,0x40,0x08,0x40,0x3E,0x7C,0x00,0x00,0x00,0x00,0x00,0x00 }; static void TransmitByte(uint8 byte); static void SelectRow(uint8 row); static void FlipLatchLine(void);
static void TransmitByte(uint8 byte) { uint8 i; for(i = 0 ; i < 8 ; i ++) { if(byte & (1 << i)) { DOTLED_LINE_PORT |= _BV(DOTLED_LINE_SDA); } else { DOTLED_LINE_PORT &= ~_BV(DOTLED_LINE_SDA); } //__delay_cycles(100); DOTLED_LINE_PORT |= _BV(DOTLED_LINE_SCKH); //__delay_cycles(100); DOTLED_LINE_PORT &= ~_BV(DOTLED_LINE_SCKH); //__delay_cycles(100); } }
static void SelectRow(uint8 row) { //row -= 1; row |= DOTLED_ROW_PIN & 0xe0; DOTLED_ROW_PORT = row; }
static void FlipLatchLine(void) { DOTLED_LINE_PORT |= _BV(DOTLED_LINE_SCKT); DOTLED_LINE_PORT &= ~_BV(DOTLED_LINE_SCKT); }
void InitDotLedPort(void) { DOTLED_LINE_PORT &= ~(_BV(DOTLED_LINE_SCKT) | _BV(DOTLED_LINE_SCKH)); DOTLED_LINE_PORT |= _BV(DOTLED_LINE_SDA); DOTLED_LINE_DDR |= _BV(DOTLED_LINE_SCKT) | _BV(DOTLED_LINE_SCKH) | _BV(DOTLED_LINE_SDA); DOTLED_ROW_PORT |= 0x1f; DOTLED_ROW_PORT &= 0xf0; DOTLED_ROW_DDR |= 0x1f; } void EnableRow(boolean IsEnable) { if(IsEnable) { DOTLED_ROW_PORT &= ~_BV(DOTLED_ROW_E); } else { DOTLED_ROW_PORT |= _BV(DOTLED_ROW_E); } } void PrintDotLed(uint8 * buffer) { uint8 i , tmp; for(i = 0 ; i < 16 ; i ++) { tmp = *buffer ++; TransmitByte(~tmp); tmp = *buffer ++; TransmitByte(~tmp); SelectRow(i); FlipLatchLine(); } } void main(void) { InitDotLedPort(); EnableRow(TRUE); while(1) { PrintDotLed(font); __delay_cycles(5000); } }
//---------------------------------------------------- config.h文件
#ifndef _CONFIG_H #define _CONFIG_H
//#define GCCAVR
#define CPU_CYCLES 7372800L
#ifndef GCCAVR #define _BV(bit) (1 << (bit)) #endif
#define MSB 0x80 #define LSB 0x01
#define FALSE 0 #define TRUE 1 typedef unsigned char uint8; typedef unsigned int uint16; typedef unsigned long uint32; typedef unsigned char boolean; #include <ioavr.h> #include <inavr.h>
#include "dotled.h" #endif
//-----
標簽：
16
點陣顯示
漢字
顯示程序
上傳時間：
2013-11-18
上傳用戶：mnacyf
