1 ; This code was copied from Microchip Application Note AN593 -- 2 ; `Serial Port Routines Without Using the RTCC' 3 4 ; These routines were written to work on the PICDEM1 hardware 5 ; The frequency of the clock is 16MHz and the hardware uses no 6 ; handshake 7 ; TX -> RA3 8 ; RX -> RA2 9 10 indf: equ 0 ; Indirect File 11 tmr0: equ 1 ; Timer 0 12 pcl: equ 2 ; Program Counter Low 13 14 status: equ 3 ; Status Register 15 #define irp status,7 ; Indirect Register Bank Select 16 #define rp1 status,6 ; Register Page 1 17 #define rp0 status,6 ; Register Page 0 18 #define to status,4 ; Time Out 19 #define pd status,3 ; Power Down 20 #define z status,2 ; Zero Flag 21 #define dc status,1 ; Digital Carry Flag 22 #define c status,0 ; Carry Flag 23 24 fsr: equ 4 ; FSR 25 26 porta: equ 5 ; Port A I/O Register 27 #define ra5 porta,5 ; Port A Bit 5 28 #define ra4 porta,4 ; Port A Bit 4 29 #define ra3 porta,3 ; Port A Bit 3 30 #define ra2 porta,2 ; Port A Bit 2 31 #define ra1 porta,1 ; Port A Bit 1 32 #define ra0 porta,0 ; Port A Bit 0 33 34 portb: equ 6 ; Port B I/O Register 35 #define rb7 portb,7 ; Port B Bit 7 36 #define rb6 portb,6 ; Port B Bit 6 37 #define rb5 portb,5 ; Port B Bit 5 38 #define rb4 portb,4 ; Port B Bit 4 39 #define rb3 portb,3 ; Port B Bit 3 40 #define rb2 portb,2 ; Port B Bit 2 41 #define rb1 portb,1 ; Port B Bit 1 42 #define rb0 portb,0 ; Port B Bit 0 43 44 portc: equ 6 ; Port B I/O Register 45 #define rc7 portc,7 ; Port C Bit 7 46 #define rc6 portc,6 ; Port C Bit 6 47 #define rc5 portc,5 ; Port C Bit 5 48 #define rc4 portc,4 ; Port C Bit 4 49 #define rc3 portc,3 ; Port C Bit 3 50 #define rc2 portc,2 ; Port C Bit 2 51 #define rc1 portc,1 ; Port C Bit 1 52 #define rc0 portc,0 ; Port C Bit 0 53 54 option: equ 1 ; Option register 55 #define rbpu option,7 ; Register B Pull-up (1=on;0=off) 56 #define intedg option,6 ; Interrupt Edge Select (1=rising;0=falling) 57 #define t0cs option,5 ; Timer 0 Clock Source Select (1=RA4;0=Ins. Clock) 58 #define t0se option,4 ; Timer 0 Source Edge Select (1=falling;0=rising) 59 #define psa option,3 ; Prescaler Assignment (1=WDT;0=Timer0) 60 #define ps2 option,2 ; Prescaler Bit 2 61 #define ps1 option,1 ; Prescaler Bit 1 62 #define ps0 option,0 ; Prescaler Bit 0 63 64 intcon: equ 0xe ; Interrupt Control 65 #define gie intcon,7 ; Global Interrupt Enable 66 #define peie intcon,6 ; Peripheral Inerrupt Enable 67 #define t0ie intcon,5 ; Timer 0 Overflow Interrupt Enable 68 #define inte intcon,4 ; External Interrupt Enable 69 #define rbie intcon,3 ; RB Port Change Interrupt Enable 70 #define t0if intcon,2 ; TMR0 Overflow Interrupt Enable 71 #define intf intcon,1 ; RB0/INT External Interrupt Enable 72 #define rbif intcon,0 ; RB7:RB4 Port Change Status 73 74 last_program_address: equ 0xfff; Last program address 75 76 77 processor pic16c63a 78 configure osc=xt, wdte=off, pwrte=off, cp=off, mclre=off, bowden=off 79 80 clockrate: equ 16000000 81 baudrate: equ 9600 82 83 fclk: equ (clockrate/4) 84 ; The value baudconst must be an 8-bit value only 85 baudconst: equ (((fclk/baudrate)/3)-2) 86 count: equ 0x10 87 txreg: equ 0x11 88 rcreg: equ 0x11 89 delay: equ 0x12 90 tempa: equ 0x13 91 hi: equ 0x10 92 lo: equ 0x11 93 gpram: equ 0x15 94 #define tx porta,3 95 #define rx porta,2 96 #define tempa7 tempa,7 97 org 0x0 98 start: 99 0000 205a call wait 100 0001 300f movlw 0xf 101 0002 0085 movwf porta 102 0003 3007 movlw 0x7 103 0004 0065 tris porta 104 0005 0186 clrf portb 105 0006 0100 clrw 106 0007 0066 tris portb 107 0008 30a5 movlw 0xa5 108 0009 0615 xorwf gpram,w 109 000a 1903 btfsc z 110 000b 2064 call mclr 111 000c 30a5 movlw 0xa5 112 000d 0095 movwf gpram 113 114 115 000e 302f movlw 0x2f 116 000f 0093 movwf tempa 117 0010 3038 movlw 0x38 118 0011 0062 option 119 0012 0000 nop ; clrf rtcc 120 s1check: 121 0013 0000 nop ; movf rtcc,w 122 0014 1903 btfsc z ; if S1 pressed then skip 123 0015 2813 goto s1check 124 125 next: 126 0016 0a93 incf tempa,f 127 0017 1b93 btfsc tempa7 128 0018 2861 goto AllDone 129 0019 0813 movf tempa,w 130 001a 2020 call transmit 131 001b 2037 call receive 132 001c 0213 subwf tempa,w 133 001d 1903 btfsc z 134 001e 2847 goto fail 135 001f 2816 goto next 136 137 138 transmit: 139 0020 0091 movwf txreg 140 0021 1185 bcf tx ; send start bit 141 0022 3088 movlw baudconst 142 0023 0092 movwf delay 143 0024 3009 movlw 9 144 0025 0090 movwf count 145 txbaudwait: 146 0026 0b92 decfsz delay,f 147 0027 2826 goto txbaudwait 148 0028 3088 movlw baudconst 149 0029 0092 movwf delay 150 002a 0b90 decfsz count,f 151 002b 2830 goto SendNextBit 152 002c 3009 movlw 9 153 002d 0090 movwf count 154 002e 1585 bsf tx 155 002f 3400 retlw 0 156 SendNextBit: 157 0030 0c91 rrf txreg,f 158 0031 1c03 btfss c 159 0032 2835 goto setlo 160 0033 1585 bsf tx 161 0034 2826 goto txbaudwait 162 setlo: 163 0035 1185 bcf tx 164 0036 2826 goto txbaudwait 165 166 167 receive: 168 0037 1905 btfsc rx ; wait for receive 169 0038 2837 goto receive 170 rxbaudwait: 171 0039 0b92 decfsz delay,f 172 003a 2839 goto rxbaudwait 173 003b 3088 movlw baudconst 174 003c 0092 movwf delay 175 003d 0b90 decfsz count,f 176 003e 2842 goto RecvNextBit 177 003f 3009 movlw 9 178 0040 0090 movwf count 179 0041 3400 retlw 0 180 RecvNextBit: 181 0042 1003 bcf c 182 0043 1905 btfsc rx 183 0044 1403 bsf c 184 0045 0c91 rrf rcreg,f 185 0046 2839 goto rxbaudwait 186 187 fail: 188 0047 0986 comf portb,f 189 0048 204a call halfsec 190 0049 2847 goto fail 191 halfsec: 192 004a 0190 clrf hi 193 004b 0191 clrf lo 194 hsloop: 195 004c 0000 nop 196 004d 0000 nop 197 004e 0000 nop 198 004f 0000 nop 199 0050 0000 nop 200 0051 0000 nop 201 0052 0000 nop 202 0053 0000 nop 203 0054 0000 nop 204 0055 0b91 decfsz lo,f 205 0056 284c goto hsloop 206 0057 0b90 decfsz hi,f 207 0058 284c goto hsloop 208 0059 3400 retlw 0 209 210 wait: 211 005a 0190 clrf hi 212 005b 0191 clrf lo 213 dly: 214 005c 0b91 decfsz lo,f 215 005d 285c goto dly 216 005e 0b90 decfsz hi,f 217 005f 285c goto dly 218 0060 3400 retlw 0 219 220 AllDone: 221 0061 3055 movlw 0x55 222 0062 0086 movwf portb 223 inifinite: 224 0063 2863 goto inifinite 225 226 mclr: 227 0064 0186 clrf portb 228 0065 0386 decf portb,f 229 0066 0195 clrf gpram 230 s3check: 231 0067 1885 btfsc ra1 232 0068 2867 goto s3check 233 0069 0186 clrf portb 234 infloop: 235 006a 286a goto infloop 236 org 0x1ff 237 01ff 2800 goto start 238 end