; i2c_eeprom.asm ; ; Copyright (C) 2006,2007 Nuno Sucena Almeida ; ; This program is free software; you can redistribute it and/or modify ; it under the terms of the GNU General Public License as published by ; the Free Software Foundation; either version 2 of the License, or ; (at your option) any later version. ; ; This program is distributed in the hope that it will be useful, ; but WITHOUT ANY WARRANTY; without even the implied warranty of ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ; GNU General Public License for more details. ; ; You should have received a copy of the GNU General Public License ; along with this program; if not, write to the Free Software ; Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA ; ; simple support for communication with ; the eeprom 24AA512 through the i2c bus include include udata ; eeprom control byte i2c_ee_control res 1 ; eeprom LOW and HIGH address i2c_ee_addr_L res 1 i2c_ee_addr_H res 1 ;; usually stores the last read byte from the eeprom after ;; the appropriate routine is called. i2c_ee_data res 1 ;; temporary counter for the number of bytes to read when using the ;; sequential read routine. i2c_ee_nbytes res 1 ;-------------------------------------------------------------------- ; external functions extern i2c_send extern i2c_receive extern i2c_debug extern delay10 extern delay100 ;; extern delayms extern uart_receive extern uart_send ;-------------------------------------------------------------------- ; external symbols extern i2c_status extern i2c_ioe_matrix code ;-------------------------------------------------------------------- ; set eeprom address to 1010 000 0 ; 1010 - control code ; 000 - chip select : we have only one on the controller ; board with address 000. ; 0 - R/W ; see page 8 of 24AA512 i2c_eeprom_setup: movlw B'10100000' banksel i2c_ee_control movwf i2c_ee_control ;; clear data banksel i2c_ee_data clrf i2c_ee_data return ;-------------------------------------------------------------------- ; set i2c eeprom address for next read/write operation ; see page 13, figure 8-2 of the 24AA512 manual i2c_eeprom_set_address: i2c_eeprom_set_address_start: ; wait for clock line to be free i2c_SCL_WAIT ; send start i2c_START ; ; we want to send ACK ; i2c_SET_SEND_ACK ; set control bit to WRITE to select address banksel i2c_ee_control bcf i2c_ee_control,0 ; send control byte: movf i2c_ee_control,W call i2c_send ; check ACK and if error, jump to START i2c_CHECK_ACK i2c_eeprom_set_address_start ; send address high byte banksel i2c_ee_addr_H movf i2c_ee_addr_H,W call i2c_send ; check ACK and if error, jump to START i2c_CHECK_ACK i2c_eeprom_set_address_start ; send address low byte banksel i2c_ee_addr_L movf i2c_ee_addr_L,W call i2c_send ; check ACK and if error, jump to START i2c_CHECK_ACK i2c_eeprom_set_address_start return ;-------------------------------------------------------------------- ; read a byte from the eeprom connected to the i2c bus. the address ; must be previously set by the 'set_address' routine. ; see pages 12,13 of the 24AA512 manual ; the data is returned in 'W' i2c_eeprom_random_read: ; wait for clock line to be free i2c_SCL_WAIT ; send start i2c_START ; set control bit to READ banksel i2c_ee_control bsf i2c_ee_control,0 ; send control byte: movf i2c_ee_control,W call i2c_send ; check ACK and if error, jump to beginning i2c_CHECK_ACK i2c_eeprom_random_read ; we don't want to send ACK i2c_SET_SEND_NACK ; read byte and put it in 'i2c_ee_data' ; to save it call i2c_receive banksel i2c_ee_data movwf i2c_ee_data ; check ACK and if error, jump to beginning i2c_CHECK_ACK i2c_eeprom_random_read ; all done, send STOP i2c_STOP ; put data back to 'W' banksel i2c_ee_data movf i2c_ee_data,W return ;-------------------------------------------------------------------- ; read N bytes from the eeprom connected to the i2c bus. the address ; must be previously set by the 'set_address' routine. ; see pages 12,13 of the 24AA512 manual, section 8.3 and figure 8-3 ; ; the number of bytes to read must be specified by the user using the ; 'W' register i2c_eeprom_sequential_read: banksel i2c_ee_nbytes movwf i2c_ee_nbytes ;; initialize the indirect addressing register movlw i2c_ioe_matrix movwf FSR i2c_eeprom_sequential_read_cont: ; wait for clock line to be free i2c_SCL_WAIT ; send start i2c_START ; we want to send ACK i2c_SET_SEND_ACK ; set control bit to READ banksel i2c_ee_control bsf i2c_ee_control,0 ; send control byte: movf i2c_ee_control,W call i2c_send ; check ACK and if error, jump to beginning i2c_CHECK_ACK i2c_eeprom_sequential_read_cont i2c_eeprom_sequential_read_loop: ; read byte call i2c_receive ; check ACK and if error, jump to beginning i2c_CHECK_ACK i2c_eeprom_sequential_read ;put byte in 'i2c_ioe_matrix' using indirect addressing. banksel i2c_ioe_matrix movwf INDF incf FSR,F ;; send to uart for debugging call uart_send ;; check the byte counter to see if we are done banksel i2c_ee_nbytes decfsz i2c_ee_nbytes,F goto i2c_eeprom_sequential_read_loop ;; all done, send STOP i2c_STOP return ;-------------------------------------------------------------------- ; write a byte to the eeprom connected to the i2c bus. the address ; must be previously set by the 'set_address' and the byte data in the ; 'W' register. ; see pages 9,10 from 24AA512 manual i2c_eeprom_random_write: ; send data byte: ; banksel i2c_ee_data ; movf i2c_ee_data,W call i2c_send ; check ACK and if error, jump to beginning i2c_CHECK_ACK i2c_eeprom_random_write ; all done, send STOP i2c_STOP ;; wait longer ; call delayms ; #warning see section 7.0 for the fact that ACK is not returned while device ; is busy return ;-------------------------------------------------------------------- ; this routine gets 3 values from the uart, which correspond to the ; i2c eeprom HI and LO address and the byte to write. i2c_eeprom_write_uart: ;; get and set i2c eeprom HI address call uart_receive banksel i2c_ee_addr_H movwf i2c_ee_addr_H ;; get and set i2c eeprom LO address call uart_receive banksel i2c_ee_addr_L movwf i2c_ee_addr_L ;; set i2c eeprom address: call i2c_eeprom_set_address ;; read uart and send byte to i2c eeprom call uart_receive call i2c_eeprom_random_write return ;-------------------------------------------------------------------- ; this routine gets 2 values from the uart, which correspond to the ; i2c eeprom HI and LO address and sends through the uart the read ; data byte i2c_eeprom_read_uart: ;; get and set i2c eeprom HI address call uart_receive banksel i2c_ee_addr_H movwf i2c_ee_addr_H ;; get and set i2c eeprom LO address call uart_receive banksel i2c_ee_addr_L movwf i2c_ee_addr_L ;; set i2c eeprom address: call i2c_eeprom_set_address ;; read byte from i2c eeprom and send it through the uart call i2c_eeprom_random_read call uart_send return ;-------------------------------------------------------------------- ; this routine gets 2 values from the uart, which correspond to the ; i2c eeprom HI and LO initial address and then calls the sequential ; read i2c_eeprom_read_sequential_uart: ;; get and set i2c eeprom HI address call uart_receive banksel i2c_ee_addr_H movwf i2c_ee_addr_H ;; get and set i2c eeprom LO address call uart_receive banksel i2c_ee_addr_L movwf i2c_ee_addr_L ;; set i2c eeprom address: call i2c_eeprom_set_address ;; read 'MATRIX_SIZE' bytes from i2c eeprom movlw MATRIX_SIZE call i2c_eeprom_sequential_read return ;-------------------------------------------------------------------- ; this routine will start an infinite loop, where it sends a byte ; to the i2c eeprom and reads it back ; i2c_eeprom_test: ;; set i2c eeprom HI address movlw B'00000001' banksel i2c_ee_addr_H movwf i2c_ee_addr_H ;; set i2c eeprom LO address movlw B'00000001' banksel i2c_ee_addr_L movwf i2c_ee_addr_L call i2c_eeprom_set_address ;; data we want to write to the i2c eeprom ; movlw B'00100101' movlw A'&' call i2c_eeprom_random_write i2c_eeprom_test_loop: movlw 'T' call uart_send ;; trigger: banksel PORTA bsf PORTA,0 call delay100 banksel PORTA bcf PORTA,0 call delay100 ;; increment address ; banksel i2c_ee_addr_L ; incf i2c_ee_addr_L,F ; ;; set i2c eeprom address: ; call i2c_eeprom_set_address ; ;; data we want to write to the i2c eeprom ; movlw B'01110111' ; call i2c_eeprom_random_write ;; set i2c eeprom address: call i2c_eeprom_set_address movlw A':' call uart_send ;; read byte from i2c eeprom and send it through the uart call i2c_eeprom_random_read call uart_send goto i2c_eeprom_test_loop return global i2c_eeprom_setup global i2c_eeprom_set_address global i2c_eeprom_random_read global i2c_eeprom_random_write global i2c_eeprom_read_uart global i2c_eeprom_write_uart global i2c_eeprom_read_sequential_uart global i2c_eeprom_test end