; i2c_expander.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 I2C communication with ; the MCP23016 I/O Expanders include include include udata ; expander control byte i2c_ioe_control res 1 ; expander command and data LOW and HIGH (see fig 1-3,page 13) bytes. i2c_ioe_command res 1 i2c_ioe_data_1 res 1 i2c_ioe_data_2 res 1 i2c_send_cmd_tries res 1 i2c_ioe_rotate_1 res 1 ;; temp variables that will hold the values of data_1 and data_2 ;; during the vertical cycle i2c_ioe_data_temp res 1 ;; We have a 16x16 matrix, 16 vertical lines and 16 horizontal lines, ;; so if we are doing a vertical scan, we will need 2 bytes * 16 lines ;; for the complete matrix, ie 32 bytes. i2c_ioe_matrix res MATRIX_SIZE ;-------------------------------------------------------------------- ; external functions extern i2c_send extern i2c_debug extern delay10 extern uart_receive ;-------------------------------------------------------------------- ; external symbols extern i2c_status code ;-------------------------------------------------------------------- ; set I/O Expander address to 0100 000 0 ; 0100 - control code ; 000 - chip select ; 0 - R/W ; see page 4 of MCP23016 i2c_ioe_setup: movlw B'01000000' banksel i2c_ioe_control movwf i2c_ioe_control ; ************************************************* ; set all ports as output by unsetting the ; IODIR0 and IODIR1 Expander registers banksel i2c_ioe_data_1 clrf i2c_ioe_data_1 clrf i2c_ioe_data_2 ; set the command byte value for IODIR0 register movlw IODIR0 banksel i2c_ioe_command movwf i2c_ioe_command ; setup I/O expander at address 000 movlw B'01000000' banksel i2c_ioe_control movwf i2c_ioe_control call i2c_ioe_send_cmd ; setup I/O expander at address 001 movlw B'01000010' banksel i2c_ioe_control movwf i2c_ioe_control call i2c_ioe_send_cmd ; ************************************************* ; setup I/O expander at address 000 ; to have all outputs set to HIGH movlw B'01000000' banksel i2c_ioe_control movwf i2c_ioe_control movlw H'FF' banksel i2c_ioe_data_1 movwf i2c_ioe_data_1 movwf i2c_ioe_data_2 movlw GP0 banksel i2c_ioe_command movwf i2c_ioe_command call i2c_ioe_send_cmd ; ************************************************* ; setup I/O expander at address 001 ; to have all outputs set to LOW movlw B'01000010' banksel i2c_ioe_control movwf i2c_ioe_control banksel i2c_ioe_data_1 clrf i2c_ioe_data_1 clrf i2c_ioe_data_2 movlw GP0 banksel i2c_ioe_command movwf i2c_ioe_command call i2c_ioe_send_cmd ; ************************************************* ; setup Test Point pins to have the 1MHz ; clock signal movlw D'1' banksel i2c_ioe_data_1 movwf i2c_ioe_data_1 movwf i2c_ioe_data_2 movlw IOCON0 banksel i2c_ioe_command movwf i2c_ioe_command ; setup at address 000 movlw B'01000000' banksel i2c_ioe_control movwf i2c_ioe_control call i2c_ioe_send_cmd ; setup at address 001 movlw B'01000010' banksel i2c_ioe_control movwf i2c_ioe_control call i2c_ioe_send_cmd banksel i2c_ioe_data_1 clrf i2c_ioe_data_1 clrf i2c_ioe_data_2 return ;-------------------------------------------------------------------- ; write to a register in the I/O Expander. ; see table 1-3,page 4 for commands or the include file. ; see sec 1.9.2, page 13 for details and figures 1-3ff i2c_ioe_send_cmd: ;; we only allow this many errors,ie ;; data without receiving ACK movlw I2C_RETRIES banksel i2c_send_cmd_tries movwf i2c_send_cmd_tries i2c_ioe_send_cmd_start: banksel i2c_send_cmd_tries decfsz i2c_send_cmd_tries,F goto i2c_ioe_send_cmd_cont goto i2c_ioe_send_cmd_end i2c_ioe_send_cmd_cont: ; wait for clock line to be free i2c_SCL_WAIT ; send Start i2c_START ; unset R/W control bit banksel i2c_ioe_control bcf i2c_ioe_control,0 ; send Address byte: movf i2c_ioe_control,W call i2c_send ; check ACK and if error, jump to START i2c_CHECK_ACK i2c_ioe_send_cmd_start ; send Command Byte banksel i2c_ioe_command movf i2c_ioe_command,W call i2c_send ; check ACK and if error, jump to START i2c_CHECK_ACK i2c_ioe_send_cmd_start ; send Data 1 banksel i2c_ioe_data_1 movf i2c_ioe_data_1,W call i2c_send ; check ACK and if error, jump to START i2c_CHECK_ACK i2c_ioe_send_cmd_start ; send Data 2 banksel i2c_ioe_data_2 movf i2c_ioe_data_2,W call i2c_send ; check ACK and if error, jump to START i2c_CHECK_ACK i2c_ioe_send_cmd_start i2c_ioe_send_cmd_end: ; all done, send STOP i2c_STOP return ;-------------------------------------------------------------------- ; this routine i2c_ioe_rotate: ;; expander at address 000 movlw B'01000000' banksel i2c_ioe_control movwf i2c_ioe_control banksel i2c_ioe_data_1 incf i2c_ioe_data_1,F incf i2c_ioe_data_2,F movlw GP0 banksel i2c_ioe_command movwf i2c_ioe_command call i2c_ioe_send_cmd return ;-------------------------------------------------------------------- ; this routine cycles the value of the expander at address 000 so that ; we have a vertical scanning. ; It starts at 1 then, then we do a left bit rotation ; until the carrier status bit (STATUS,C) is 1 and then we go to the ; higher byte. In between it reads, using indirect addressing, the ; horizontal byte values (expander at address 001) from RAM. i2c_ioe_cycle_macro macro data_1,data_2 local i2c_ioe_cycle_macro_loop i2c_ioe_cycle_macro_loop: ;; save data values to temporary location banksel data_1 movf data_1,W movwf i2c_ioe_data_temp ;; we read the 2 bytes from RAM and send it to the ;; expander at address 001 movlw B'01000010' banksel i2c_ioe_control movwf i2c_ioe_control ;; read LOW byte value from RAM banksel i2c_ioe_matrix movf INDF,W banksel i2c_ioe_data_1 movwf i2c_ioe_data_1 ;; read HIGH byte value from RAM banksel i2c_ioe_matrix incf FSR,F movf INDF,W banksel i2c_ioe_data_2 movwf i2c_ioe_data_2 incf FSR,F ;; send byte values to expander at 001 call i2c_ioe_send_cmd ;; get back the saved data values banksel data_1 movf i2c_ioe_data_temp,W movwf data_1 clrf data_2 ;; expander at address 000 which will do the vertical cycle movlw B'01000000' banksel i2c_ioe_control movwf i2c_ioe_control ;; send data values to expander at 000 call i2c_ioe_send_cmd ;; left rotate and check if we have 'overflow' banksel data_1 rlf data_1,F btfss STATUS,C goto i2c_ioe_cycle_macro_loop endm i2c_ioe_cycle_vertical: ;; set command: movlw GP0 banksel i2c_ioe_command movwf i2c_ioe_command ;; initialize the indirect addressing register movlw i2c_ioe_matrix movwf FSR i2c_ioe_cycle_vertical_loop_1: ;; initialize lower byte at 1 and higher byte at 0. movlw D'1' banksel i2c_ioe_data_1 movwf i2c_ioe_data_1 i2c_ioe_cycle_macro i2c_ioe_data_1,i2c_ioe_data_2 i2c_ioe_cycle_vertical_loop_2: ;; we are done with the lower first 8 bits, so lets go to the ;; next higher byte. ;; initialize higher byte at 1 and higher byte at 0. movlw D'1' banksel i2c_ioe_data_2 movwf i2c_ioe_data_2 i2c_ioe_cycle_macro i2c_ioe_data_2,i2c_ioe_data_1 return ;-------------------------------------------------------------------- ; table for the vertical cycle, so that we mimic a shift-register ; i2c_ioe_cycle_table1: ; addwf PCL,F ; dt D'1',D'2',D'4',D'8',D'16',D'32',D'64',D'128' ; dt D'0',D'0',D'0',D'0',D'0' ,D'0' ,D'0' ,D'0' ;-------------------------------------------------------------------- ; this routine gets 4 values from the uart, which correspond to the ; expanders output values and then sends them through the i2c bus. i2c_ioe_set_outputs: movlw GP0 banksel i2c_ioe_command movwf i2c_ioe_command ;; expander at address 000 movlw B'01000000' banksel i2c_ioe_control movwf i2c_ioe_control ;; get first data call uart_receive banksel i2c_ioe_data_1 movwf i2c_ioe_data_1 ;; get second data call uart_receive banksel i2c_ioe_data_2 movwf i2c_ioe_data_2 call i2c_ioe_send_cmd ;; expander at address 001 movlw B'01000010' banksel i2c_ioe_control movwf i2c_ioe_control ;; get first data call uart_receive banksel i2c_ioe_data_1 movwf i2c_ioe_data_1 call uart_receive ;; get second data banksel i2c_ioe_data_2 movwf i2c_ioe_data_2 call i2c_ioe_send_cmd return global i2c_ioe_setup global i2c_ioe_send_cmd global i2c_ioe_rotate global i2c_ioe_set_outputs global i2c_ioe_cycle_vertical global i2c_ioe_matrix end