📄 part3.lst
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MPASM 03.20 Released PART3.ASM 10-24-2002 12:35:27 PAGE 1
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00001 ; COPYRIGHT 2002 BY DAVID EK. PERMISSION IS GRANTED TO FREELY USE
00002 ; THIS SOFTWARE FOR NONCOMMERCIAL PURPOSES.
00003 ;
00004 ; NOTE: USE AT YOUR OWN RISK. THE AUTHOR ASSUMES NO LIABILITY FOR DAMAGE
00005 ; INCURRED FROM THE USE OF THIS SOFTWARE.
00006 ;
00007 ; THIS IS THE CODE FOR INSTALLMENT 2 OF THE PIC WX ARTICLES IN
00008 ; THE DIGITAL QRP HOMEBREWING COLUMN OF QRP QUARTERLY, FALL 2002.
00009 ;
00010 ; PIC16F84 code for the NK0E weather station project. The purpose
00011 ; of this project is to provide a hardware interface which measures
00012 ; temperature, wind speed, wind direction, humidity, and pressure
00013 ; and communicates it to a PC via serial communications when
00014 ; requested. Note that the data collected and transmitted must be
00015 ; processed by the PC in order to obtain the actual measurement
00016 ; values (i.e. no calibration is done in the PIC code).
00017 ;
00018 ; The hardware circuit makes use of two major components: the
00019 ; PIC16F84 itself and a MAX232 TTL-RS232 level converter.
00020 ; The MAX232 converts the TTL signals from the PIC to RS232 levels
00021 ; for the PC (and vice versa).
00022 ;
00023 ; The PIC16F84 pin assignments are as follows:
00024 ;
00025 ; RA1: serial out to PC
00026 ; RA2: clock out to SHT11 temp/humid sensor
00027 ; RA3: data in/out for SHT11 temp/humid sensor
00028 ; RB0: serial in from PC (generates interrupt)
00029 ;
00030 ; This software implements the following command set:
00031 ;
00032 ; Received Reply Description
00033 ;-----------------------------------
00034 ; 't' 12345 CR LF Get the temperature raw data. Five digits
00035 ; or e1 CR LF are always returned, with leading zeroes
00036 ; or e2 CR LF if necessary, followed by a carriage return
00037 ; and line feed. See the SHT11 data sheet
00038 ; for instructions on computing the temperature.
00039 ; A return of e1 indicates that the SHT11 didn't
00040 ; acknowledge the request. A return of e2
00041 ; indicates that no data was returned by the SHT11
00042 ; within the wait period (255 ms).
00043 ; 'h' 12345 CR LF Get the humidity raw data. Five digits
00044 ; or e1 CR LF are always returned, with leading zeroes
00045 ; or e2 CR LF if necessary, followed by a carriage return
00046 ; and line feed. See the SHT11 data sheet for
00047 ; instructions on computing the humidity.
00048 ; A return of e1 indicates that the SHT11 didn't
00049 ; acknowledge the request. A return of e2
00050 ; indicates that no data was returned by the SHT11
00051 ; within the wait period (255 ms).
00052 ; 'v' version info Gets the version number of the firmware.
00053 ; returns an ASCII string followed by a
MPASM 03.20 Released PART3.ASM 10-24-2002 12:35:27 PAGE 2
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00054 ; carriage return and line feed.
00055 ;
00056 ; Written using Microchip MPLAB v5.40
00057 ;
00058 ; Please direct any questions, comments, or suggestions to the
00059 ; author: David Ek
00060 ; nk0e@earthlink.net
00061 ;
00062 ; History:
00063 ;
00064 ; Rev 1 (23 Jul 2002):
00065 ; Creation. Returns dummy temperature data. This version used
00066 ; for installment 2 of the PIC WX articles in QQ.
00067 ; Rev 2 (26 Sep 2002):
00068 ; Added code for the Sensirion SHT11 temperature/humidity sensor
00069 ; for installment 3 of the PIC WX articles in QQ.
00070 ;
00071 ;----------------------------------------------------------------
00072
00073 list p=16f84
00074 radix dec
2007 3FF9 00075 __config _CP_OFF & _WDT_OFF & _XT_OSC
00076
00077 include "p16f84.inc"
00001 LIST
00002 ; P16F84.INC Standard Header File, Version 2.00 Microchip Technology, Inc.
00136 LIST
00078
00079 ; defines:
00080
00081 ; These are used by the serial comm routines for timing. Note that
00082 ; slower speeds may not work well because the delays might be larger
00083 ; than 255, requiring the use of the prescalar.
00084
000F4240 00085 _Clkspd equ 1000000 ;external clock / 4
00002580 00086 _BaudRate equ 9600 ;desired baud rate
00000068 00087 _Period equ (_Clkspd/_BaudRate) ;clock cycles / bit
00088
0000000C 00089 _StartRxDelay equ (_Period/2 - 15)/3 ;this is how long to
00090 ;wait to get to the
00091 ;middle of the start
00092 ;bit. This is loops,
00093 ;not clock cycles.
00094
000000AD 00095 _BitRxDelay equ 277 - _Period ;this is what to load
00096 ;into TMR0 for correct
00097 ;interval between bits
00098 ;on RX
00099
000000B5 00100 _BitTxDelay equ 285 - _Period ;this is what to load
00101 ;into TMR0 for correct
00102 ;interval between bits
00103 ;on TX
MPASM 03.20 Released PART3.ASM 10-24-2002 12:35:27 PAGE 3
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00104
000000A8 00105 _StopTxDelay equ 272 - _Period ;this is what to load
00106 ;into TMR0 for correct
00107 ;interval betweeen last
00108 ;bit and stop bit on TX
00109
00110 ; defines for I/0 pins:
00111
00000000 00112 _SER_IN equ 0 ;Serial input line (PORTB)
00000001 00113 _SER_OUT equ 1 ;Serial output line (PORTA)
00000002 00114 _SHT11_SCK equ 2 ;clock line for SHT11 sensor
00115 ;(PORTA)
00000003 00116 _SHT11_DAT equ 3 ;data line for SHT11 sensor
00117 ;(PORTA)
00118
00119 ; macros for the bin-to-ascii conversion routines:
00120
00121 loadw macro arg1
00122 movlw high(arg1)
00123 movwf hi
00124 movlw low(arg1)
00125 movwf lo
00126 endm
00127 dodigit macro arg1
00128 movlw high(arg1)
00129 movwf shi
00130 movlw low(arg1)
00131 movwf slo
00132 call dosub
00133 endm
00134
00135 ; memory locations:
00136
00137 cblock 0x0C
00138
0000000C 00139 BitCount ;number of bits left to send or
00140 ;receive, not including start & stop
00141 ;bits
00142
0000000D 00143 RXChar ;received character while being received
0000000E 00144 RXBuff ;most recently received character
00145
0000000F 00146 TXChar ;character to transmit
00147
00000010 00148 SerialReg ;status register:
00149 ;bit 0: on if character has been
00150 ; received
00151 ;bit 1: on if busy with RX/TX
00152 ;bit 2: on if sending, off if receiving
00153 ;bit 3: on if next bit to send is stop bit
00154
00000011 00155 WSave ;copy of W register
00156
MPASM 03.20 Released PART3.ASM 10-24-2002 12:35:27 PAGE 4
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00000012 00157 SSave ;copy of the Status register
00158
00000013 00159 SHT11Byte ;a byte of data sent to or returned by the SHT11
00160
00000014 00161 counter ;generic counter register
00162
00000015 00163 hi ;hi byte for number to be converted to ascii
00000016 00164 lo ;lo byte for number to be converted to ascii
00000017 00165 shi ;hi byte for subtractor for conversion to ascii
00000018 00166 slo ;lo byte for subtractor for conversion to ascii
00000019 00167 digit ;ascii digit converted from binary. Also used as
00168 ;input to SendErrorCode
00169
0000001A 00170 MSDelay ;register for WaitMS timing
00171
00172 endc
00173
0000 00174 org 0x00
0000 292A 00175 goto Main
00176
0004 00177 org 0x04
00178
00179 ;--------------------------------------------------------------------
00180 ;-----Serial Communication Routines----------------------------------
00181 ;--------------------------------------------------------------------
00182 ;
00183 ; The serial comm routines generate 1 start bit, 8 data bits, 1 stop bit,
00184 ; no parity. The baud rate is determined by the delay programmed
00185 ; into the onboard timer. The sending and receiving is interrupt driven,
00186 ; meaning other tasks can be carried on while the characters are being
00187 ; sent and received.
00188 ;
00189 ;-----Main Interrupt Routine-----------------------------------------
00190 ;
00191 ; for timing: 4 cycles from interrupt time to get here.
00192
00193 ; Save the W and STATUS registers:
00194
0004 00195 Int
0004 0091 00196 movwf WSave
0005 0E03 00197 swapf STATUS,W ;use swapf to prevent any
0006 0092 00198 movwf SSave ;status flags from being changed
00199
00200 ; cycles so far since interrupt occurred: 7
00201
00202 ; Okay, I'm doing something goofy here. Instead of actually checking
00203 ; the overflow bits themselves, I'm using the enable bits to determine
00204 ; which interrupt occurred. I can do this because there should only
00205 ; ever be one type of interrupt active at a time. The problem with
00206 ; checking the overflow bits is that the T0IF bit can get set even
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