;********************************************************************** ; * ; Filename: wiresndr.asm * ; Date: 23 Nov 1999 * ; File Version: 3 * ; * ; Author: Chris White (whitecf@bcs.org.uk) * ; Company: Monitor Computing Services Ltd. * ; * ;********************************************************************** ; * ; Copyright (C) 1999 Monitor Computing Services Ltd. * ; * ; 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 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 (http://www.gnu.org/copyleft/gpl.html) along with this * ; program; if not, write to: * ; The Free Software Foundation Inc., * ; 59 Temple Place - Suite 330, * ; Boston, MA 02111-1307, * ; USA. * ; * ;********************************************************************** ; * ; Notes: Bod test program excersising simple sending telemetry * ; interface via asynchronous serial @ 5K baud. * ; * ; 'Wire' interface, asynchronous serial @ 5K baud * ; Port A 4 - Rx, 3 - Tx * ; * ; * ; Data nibbles are transmitted as individual bytes. In * ; each transmitted byte the 'low' nibble gives the data * ; nibble's 'address', 0 - 15, and the 'high' nibble the * ; data nibble's data value. * ; This transmitter generates the data nibbles with address * ; values of 0 and 1 from the input byte value present on * ; it's input port (address 0 == input byte low nibble, * ; address 1 == high nibble). * ; If this transmitter is an 'intermediary' in a 'data * ; stream' it listens for data from 'up stream' * ; transmitters. This is then forwarded 'down stream' after * ; having 2 (the number of data nibbles generated by this * ; transmitter) added to it's address. * ; The forwarded data's addresses are examined and when * ; address 2 has been forwarded (which would have been sent * ; as address 0 by the immediately 'up stream' transmitter) * ; this node appends it's own data to the 'stream'. * ; On start up the transmitter enters a delay loop in which * ; it examines the state of it's Rx data bit. If this * ; remains high throughout the loop the the node assumes it * ; is at the 'head' of the 'data stream'. It then proceeds * ; to transmit it's data without waiting for data from any * ; 'up stream' transmitter. * ; * ;********************************************************************** list p=16C84 ;********************************************************************** ; Include and configuration directives * ;********************************************************************** #include __CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON & _XT_OSC ; '__CONFIG' directive is used to embed configuration data within .asm file. ; The lables following the directive are located in the respective .inc file. ; See respective data sheet for additional information on configuration word. #include ;********************************************************************** ; Constant definitions * ;********************************************************************** PORTASTATUS EQU B'00000000' ; Initial port status, all bits set as output PORTBSTATUS EQU B'11111111' ; Initial port status, all bits set as input RTCCINT EQU 158 ; 1Mhz / 100 (adjusted for RTCC write inhibit) = 10Khz INT5KBIT EQU 2 ; Interrupts per serial bit @ 5K baud INT5KINI EQU 3 ; Interrupts per initial Rx serial bit @ 5K (start bit) INT2K5BIT EQU 4 ; Interrupts per serial bit @ 2K5 baud INT2K5INI EQU 6 ; Interrupts per initial Rx serial bit @ 2K5 (start bit) INTMILLI EQU 10 ; Interrupts per millisecond CLKPORT EQU PORTA ; Clock tick output port CLKBIT EQU 2 ; Clock tick output on Port A bit 2 ; 'Up' interface constants RXUFLAG EQU 0 ; 'Up' receive byte buffer 'loaded' status bit RXUERR EQU 1 ; 'Up' receive error status bit RXUBREAK EQU 2 ; 'Up' received 'break' status bit TXUFLAG EQU 3 ; 'Up' transmit byte buffer 'clear' status bit TXUTRIS EQU TRISA ; 'Up' side Tx port direction register TXUPORT EQU PORTA ; 'Up' side Tx port data register TXUBIT EQU 3 ; Tx on Port A bit 3 RXUTRIS EQU TRISA ; 'Up' side Rx port direction register RXUPORT EQU PORTA ; 'Up' side Rx port data register RXUBIT EQU 4 ; Rx on Port A bit 4 ; Telemetry constants INPORT EQU PORTB LOWMASK EQU 0x0F ; Mask to isolate low 'nibble' of byte HIGHMASK EQU 0xF0 ; Mask to isolate high 'nibble' of byte ;********************************************************************** ; Variable definitions * ;********************************************************************** CBLOCK 0x0C ; Status and accumulator storage registers pclath_isr ; PCLATH register store during ISR w_isr ; 'w' register, accumulator, store during ISR status_isr ; status register store during ISR ; Interface registers serStatus ; Serial I/F status flags ; 'Up' side interface registers serURxTmr ; Interrupt counter for serial bit timing serURxReg ; Data shift register serURxByt ; Data byte buffer serURxBitCnt ; Bit down counter serUTxTmr ; Interrupt counter for serial bit timing serUTxReg ; Data shift register serUTxByt ; Data byte buffer serUTxBitCnt ; Bit down counter ; Telemetry registers intCount ; Free running interrupt counter for timing delays telemData ; Telemetry data to be transmitted ENDC ;********************************************************************** ; Reset vector * ;********************************************************************** ORG 0x000 ; Processor reset vector goto Main ; Jump to beginning of program ;********************************************************************** ; Interrupt vector * ;********************************************************************** ORG 0x004 ; Interrupt vector location goto BeginISR ; Jump to interrupt service routine ;********************************************************************** ; Link and interface routine macro invocations * ;********************************************************************** EnableRxU EnableRx RXUTRIS, RXUPORT, RXUBIT return InitRxU InitRx serURxTmr, serStatus, RXUFLAG, RXUERR, RXUBREAK return SrvcRxU ServiceRx serURxTmr, RXUPORT, RXUBIT, serURxBitCnt, INT5KINI, serStatus, RXUERR, RXUBREAK, serURxReg, serURxByt, RXUFLAG, INT5KBIT EnableTxU EnableTx TXUTRIS, TXUPORT, TXUBIT return InitTxU InitTx serUTxTmr, serStatus, TXUFLAG return SrvcTxU ServiceTx serUTxTmr, serStatus, serUTxByt, serUTxReg, TXUFLAG, serUTxBitCnt, INT5KBIT, TXUPORT, TXUBIT, 0, 0 LinkURx SerURx SerialRx serStatus, RXUFLAG, serURxByt LinkUTx SerUTx SerialTx serStatus, TXUFLAG, serUTxByt ;********************************************************************** ; Interrupt service routine (ISR) code * ;********************************************************************** BeginISR movwf w_isr ; Save off current W register contents movf STATUS,W ; Move status register into W register movwf status_isr ; save off contents of STATUS register movf PCLATH,W ; Move PCLATH register into W register movwf pclath_isr ; save off contents of PCLATH register btfss INTCON,T0IF ; Skip if RTCC interrupt flag is set ... goto EndISR ; ... otherwise jump to end of service routine BANKSEL TMR0 ; Ensure register page 0 is selected #ifdef CLKPORT bcf CLKPORT,CLKBIT ; Set clock outData low #endif bcf INTCON,T0IF ; Clear the RTCC interrupt bitflag movlw RTCCINT addwf TMR0,F ; Reload RTCC call SrvcRxU ; Perform up interface Rx service call SrvcTxU ; Perform up interface Tx service decf intCount,F ; Decrement free running interrupt counter #ifdef CLKPORT bsf CLKPORT,CLKBIT ; Set clock outData high #endif EndISR movf pclath_isr,W ; Retrieve copy of PCLATH register movwf PCLATH ; Restore pre-isr PCLATH register contents movf status_isr,W ; Retrieve copy of STATUS register movwf STATUS ; Restore pre-isr STATUS register contents swapf w_isr,F swapf w_isr,W ; Restore pre-isr W register contents retfie ; Return from interrupt ;********************************************************************** ; Main program code * ;********************************************************************** Main clrf PORTA ; Clear I/O ports clrf PORTB BANKSEL OPTION_REG ; Select register page 1 movlw PORTASTATUS ; Program I/O port bit directions movwf TRISA movlw PORTBSTATUS movwf TRISB clrf OPTION_REG bsf OPTION_REG,NOT_RBPU bsf OPTION_REG,INTEDG bsf OPTION_REG,PSA BANKSEL TMR0 ; Select register page 0 movlw PORTASTATUS ; For Port A need to write one to each bit ... movwf PORTA ; ... being used for input ; Initialise variables ; Initialise serial link SerInit serStatus, serUTxTmr, serUTxReg, serUTxByt, serUTxBitCnt, serURxTmr, serURxReg, serURxByt, serURxBitCnt call EnableRxU call InitRxU call EnableTxU call InitTxU clrf intCount ; Set free running interrupt ... decf intCount,F ; ... counter to 0xFF clrf telemData ; Initialise interrupts movlw RTCCINT movwf TMR0 ; Load RTCC clrf INTCON bsf INTCON,T0IE ; Enable RTCC interrupts bsf INTCON,GIE ; Enable interrupts Startdelay movf intCount,F ; Test free running interrupt counter btfss STATUS,Z ; Skip if it's reached zero ... goto Startdelay ; ... otherwise stay in delay loop decf intCount,F ; Set free running interrupt counter to 0xFF Startloop btfss RXUPORT,RXUBIT ; Skip if Rx data input is high ... goto Rxloop ; ... otherwise act as 'forwarding' node movf intCount,F ; Test free running interrupt counter btfss STATUS,Z ; Skip if it's reached zero ... goto Startloop ; ... otherwise stay in start loop Sendloop call SendData ; Become 'head' node, initiating data sending goto Sendloop Rxloop call LinkURx ; Check for data from 'up stream' node btfss STATUS,Z ; Skip if data received ... goto Rxloop ; ... otherwise keep waiting movwf telemData ; Save received telemetry data incf telemData,F ; Increment, twice, address part of data incf telemData,F call Txloop ; Forward modified data on 'down stream' movf telemData,W ; Retrieve modified data andlw LOWMASK ; Isolate address part of data xorlw 2 ; Test for address 2 (incremented from 0) btfsc STATUS,Z ; Skip if address is not 2 ... call SendData ; ... otherwise append own data to stream goto Rxloop ; Wait for more 'up stream' data to arrive Txloop movf telemData,W ; Get telemetry data ... movwf FSR ; ... into FSR in order to transmit call LinkUTx ; Attempt to transmit telemetry data btfss STATUS,Z ; Skip if data sent ... goto Txloop ; ... otherwise keep trying to transmit return SendData movf INPORT,W ; Get input data andlw HIGHMASK ; Isolate high nibble movwf telemData ; Move to telemtry data register bsf telemData,0 ; Set address part to 1 call Txloop ; Send data 'down stream' swapf INPORT,W ; Get input data, swapping nibbles andlw HIGHMASK ; Isolate low nibble (of original input data) movwf telemData ; Move to telemtry data register goto Txloop ; Send data 'down stream' end ; directive 'end of program'