私は C の初心者です。外部 eeprom (AT24c02B) に読み書きしてから、eeprom に保存されているデータ バイトを PORTB の LED や LCD に表示しようとしています。したがって、データがeepromに正常に保存されたことがわかります。
PORTB の LED はアクティブ LOW です。
コードは次のとおりです。cvAVR ヘルプから入手しました。
#include <mega16a.h>
// Alphanumeric LCD functions
#include <alcd.h>
// Declare your global variables here
// TWI functions
#include <twi.h>
#include <delay.h>
/* 7 bit TWI bus slave address of the AT24C02B 2kbyte EEPROM */
#define EEPROM_TWI_BUS_ADDRESS (0xA0 >> 1)
void main(void)
{
// Declare your local variables here
struct
{
struct
{
unsigned char msb;
unsigned char lsb;
} addr;
unsigned char data;
} twi_eeprom;
unsigned char eeprom_rd_data;
// Input/Output Ports initialization
// Port A initialization
// Function: Bit7=Out Bit6=Out Bit5=Out Bit4=Out Bit3=Out Bit2=Out Bit1=Out Bit0=Out
DDRA=(1<<DDA7) | (1<<DDA6) | (1<<DDA5) | (1<<DDA4) | (1<<DDA3) | (1<<DDA2) | (1<<DDA1) | (1<<DDA0);
// State: Bit7=0 Bit6=0 Bit5=0 Bit4=0 Bit3=0 Bit2=0 Bit1=0 Bit0=0
PORTA=(0<<PORTA7) | (0<<PORTA6) | (0<<PORTA5) | (0<<PORTA4) | (0<<PORTA3) | (0<<PORTA2) | (0<<PORTA1) | (0<<PORTA0);
// Port B initialization
// Function: Bit7=Out Bit6=Out Bit5=Out Bit4=Out Bit3=Out Bit2=Out Bit1=Out Bit0=Out
DDRB=(1<<DDB7) | (1<<DDB6) | (1<<DDB5) | (1<<DDB4) | (1<<DDB3) | (1<<DDB2) | (1<<DDB1) | (1<<DDB0);
// State: Bit7=1 Bit6=1 Bit5=1 Bit4=1 Bit3=1 Bit2=1 Bit1=1 Bit0=1
PORTB=(1<<PORTB7) | (1<<PORTB6) | (1<<PORTB5) | (1<<PORTB4) | (1<<PORTB3) | (1<<PORTB2) | (1<<PORTB1) | (1<<PORTB0);
// TWI initialization
// Mode: TWI Master
// Bit Rate: 100 kHz
twi_master_init(100);
// Alphanumeric LCD initialization
// Connections are specified in the
// Project|Configure|C Compiler|Libraries|Alphanumeric LCD menu:
// RS - PORTA Bit 0
// RD - PORTA Bit 1
// EN - PORTA Bit 2
// D4 - PORTA Bit 4
// D5 - PORTA Bit 5
// D6 - PORTA Bit 6
// D7 - PORTA Bit 7
// Characters/line: 16
lcd_init(16);
// Global enable interrupts
#asm("sei")
/* write the byte 0x55 to the AT24C02B EEPROM address 0x210 */
twi_eeprom.addr.msb=0x02;
twi_eeprom.addr.lsb=0x10;
twi_eeprom.data=0x55;
twi_master_trans(EEPROM_TWI_BUS_ADDRESS,(unsigned char *) &twi_eeprom,3,0,0);
/* 10ms delay to complete the write operation */
delay_ms(10);
/* read the byte back into the eeprom_rd_data variable */
twi_master_trans(EEPROM_TWI_BUS_ADDRESS,(unsigned char *) &twi_eeprom,2,&eeprom_rd_data,1);
while (1)
{
// Place your code here
PORTB = ; //What variable should I call?
delay_ms(3000);
}
}
twi.h
/******************************************************************************
TWI driver library for the CodeVisionAVR C V2.05.1+ Compiler
Copyright (C) 2010-2011 Pavel Haiduc, HP InfoTech S.R.L., All rights reserved.
*******************************************************************************/
#ifndef _TWI_INCLUDED_
#define _TWI_INCLUDED_
#include <stdbool.h>
// TWI transaction result values
#define TWI_RES_OK 0
#define TWI_RES_BUFFER_OVERFLOW 1
#define TWI_RES_ARBITRATION_LOST 2
#define TWI_RES_BUS_ERROR 3
#define TWI_RES_NACK_RECEIVED 4
#define TWI_RES_BUS_TIMEOUT 5
#define TWI_RES_FAIL 6
#define TWI_RES_UNKNOWN 7
extern unsigned char twi_tx_index; // data index in the transmit buffer
extern unsigned char twi_rx_index; // data index in the receive buffer
extern unsigned char twi_result; // holds the result of the last TWI transaction
// TWI master initialization
// bit_rate - SCL bit rate [kHz]
void twi_master_init(unsigned int bit_rate);
// function used for performing a TWI master transaction
// slave_addr - 7 bit address of the TWI slave with which the transaction must be performed
// tx_data - pointer to the buffer that holds the data to be transmitted to the slave
// tx_count - number of bytes that must be transmitted to the slave during the transaction
// rx_data - pointer to the buffer that holds the data received from the slave
// rx_count - number of bytes that must be received from the slave during the transaction
// returns true on success
bool twi_master_trans(
unsigned char slave_addr,
unsigned char *tx_data, unsigned char tx_count,
unsigned char *rx_data, unsigned char rx_count);
// TWI slave initialization
// match_any_addr - if true, the slave match address logic responds to all received addresses
// addr - 7 bit address of the TWI slave
// rx_buffer - pointer to the slave receive buffer
// rx_buffer_size - size of the slave receive buffer
// tx_buffer - pointer to the slave transmit buffer
// slave_rx_handler - pointer to the TWI slave receive processing function
// slave_tx_handler - pointer to the TWI slave transmit processing function
void twi_slave_init(
bool match_any_addr,
unsigned char addr,
unsigned char *rx_buffer,
unsigned char rx_buffer_size,
unsigned char *tx_buffer,
bool (*slave_rx_handler)(bool rx_complete),
unsigned char (*slave_tx_handler)(bool tx_complete)
);
#pragma library twi.lib
#endif
私が聞きたいのは:
1. eeprom に書き込んだ後、8 つの LED にバイトを表示するにはどの変数を呼び出せばよいですか?
例: バイトを書き込んだ後: 0xF0、PORTB の LED は 0xF0 (11110000) になります。
- インターネットで検索しましたが、まだこの行と混同しています
twi_master_trans(EEPROM_TWI_BUS_ADDRESS,(unsigned char *) &twi_eeprom,3,0,0);
twi_master_trans(EEPROM_TWI_BUS_ADDRESS,(unsigned char *) &twi_eeprom,2,&eeprom_rd_data,1);
誰か説明してくれませんか？とはどういう&twi_eeprom,3,0,0意味ですか?
デバイス : Atmega16a
プログラム : Codevision AVR 3.12
外部 eeprom : AT24c02b
回答とコメントをいただければ幸いです。
ありがとう、私の英語を許してください。
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