Frequency meter with a PICAXE 08M2 - Revision history

Shawn: /* Program listing */

2014-03-16T02:24:35Z

Program listing

← Older revision		Revision as of 19:24, 15 March 2014
Line 1:		Line 1:
	For an explanation, see [[Frequency meter]].		For an explanation, see [[Frequency meter]].
			This program runs on an inexpensive PICAXE 08M2 micro-controller with mere software timing. For better accuracy and precision, switch to a micro-controller with hardware-timer-interrupt, and/or increase oscillator frequency to decrease the time instructions take.
	===Program listing===		===Program listing===
	;2014 Shawn Reeves		;2014 Shawn Reeves
	;measures a frequency of switches between .1Hz and 50Hz		;measures a frequency of switches between .1Hz and 50Hz
			;To improve precision, and accuracy, decrease period,
			; which will require more careful measurement of instructional overhead.

	#picaxe 08m2;tell compiler which chip		#picaxe 08m2;tell compiler which chip

	;UNCOMMENT ONLY ONE OF THE FOLLOWING TO ALLOW DISPLAY METHOD		;UNCOMMENT ONLY ONE OF THE FOLLOWING TO ALLOW DISPLAY METHOD, since Serial and SPI conflict on C.0
	;#define useSerial		;#define useSerial
	#define useSPILCD		#define useSPILCD
	~~;#define useShiftLCD~~

	;Define interruptOnHigh if pin goes high when switch on, else comment out		;Define interruptOnHigh if pin goes high when switch on, else comment out
Line 38:		Line 40:

	init:		init:
	pause 100		pause 100 ;wait 0.1s for LCD to power up
	#ifdef useSPILCD		#ifdef useSPILCD
	;This routine should initialize the Electronic Assembly DOG-ME-081 8 character LCD display		;This routine should initialize the Electronic Assembly DOG-ME-081 8 character LCD display
Line 49:		Line 51:
	;The following lines from Electronic Assembly's data sheet, with cursor mode altered.		;The following lines from Electronic Assembly's data sheet, with cursor mode altered.
	;One might repeat the following command many times to get the attention of the ST7032 driver		;One might repeat the following command many times to get the attention of the ST7032 driver
	~~let~~ byteOut = %00110000 ;Function Set, 1 line, instruction table 0		byteOut = %00110000 ;Function Set, 1 line, instruction table 0
	gosub shiftout_MSBFirst		gosub shiftout_MSBFirst
	pauseus 27;recommended by ST7032 datasheet		pauseus 27;recommended by ST7032 datasheet

	~~let~~ byteOut = %00110001 ;Function Set, 1 line, instruction table 1		byteOut = %00110001 ;Function Set, 1 line, instruction table 1
	gosub shiftout_MSBFirst		gosub shiftout_MSBFirst
	pauseus 27;recommended by ST7032 datasheet		pauseus 27;recommended by ST7032 datasheet

	~~let~~ byteOut = %00110001 ;Function Set, 1 line, instruction table 1, repeat request recommended by ST7032 datasheet		byteOut = %00110001 ;Function Set, 1 line, instruction table 1, repeat request recommended by ST7032 datasheet
	gosub shiftout_MSBFirst		gosub shiftout_MSBFirst
	pauseus 27;recommended by ST7032 datasheet		pauseus 27;recommended by ST7032 datasheet

	~~let~~ byteOut = %00011100 ;Bias 1/4, 1 line LCD		byteOut = %00011100 ;Bias 1/4, 1 line LCD
	gosub shiftout_MSBFirst		gosub shiftout_MSBFirst
	pauseus 27;recommended by ST7032 datasheet		pauseus 27;recommended by ST7032 datasheet

	~~let~~ byteOut = %01010001 ;Booster off, set contrast C5, C4		byteOut = %01010001 ;Booster off, set contrast C5, C4
	gosub shiftout_MSBFirst		gosub shiftout_MSBFirst
	pauseus 27;recommended by ST7032 datasheet		pauseus 27;recommended by ST7032 datasheet

	~~let~~ byteOut = %01101010 ;set voltage follower on, gain 2/7		byteOut = %01101010 ;set voltage follower on, gain 2/7
	gosub shiftout_MSBFirst		gosub shiftout_MSBFirst
	pause 200;recommended by ST7032 datasheet		pause 200;recommended by ST7032 datasheet

	~~let~~ byteOut = %01110100 ;set contrast C3, C2, C1		byteOut = %01110100 ;set contrast C3, C2, C1
	gosub shiftout_MSBFirst		gosub shiftout_MSBFirst
	pauseus 27;recommended by ST7032 datasheet		pauseus 27;recommended by ST7032 datasheet

	~~let~~ byteOut = %00001100 ;display on, cursor off, blink cursor position		byteOut = %00001100 ;display on, cursor off, blink cursor position
	gosub shiftout_MSBFirst		gosub shiftout_MSBFirst
	pauseus 27;recommended by ST7032 datasheet		pauseus 27;recommended by ST7032 datasheet

	~~let~~ byteOut = %00000001 ;clear display, home cursor		byteOut = %00000001 ;clear display, home cursor
	gosub shiftout_MSBFirst		gosub shiftout_MSBFirst
	pauseus 2		pauseus 2

	~~let~~ byteOut = %00000110 ;entry from right to left (or opposite?), no scrolling.		byteOut = %00000110 ;entry from right to left (or opposite?), no scrolling.
	gosub shiftout_MSBFirst		gosub shiftout_MSBFirst
	high RS		high RS
Line 93:		Line 95:

	main:		main:
	;Breaking ~~10µs~~ pause into ~~1µs~~ pauses, since interrupt causes program to go to next line		;Breaking 10ms pause into 1ms pauses, since interrupt causes program to go to next line
	;;no matter how far pause was in execution.		;;no matter how far pause was in execution.
	;the timing overhead for each iteration of the following loop is about 40µs		;the timing overhead for each iteration of the following loop is about 40µs

Shawn: Created page with "For an explanation, see Frequency meter. ===Program listing=== ;2014 Shawn Reeves ;measures a frequency of switches between .1Hz and 50Hz #picaxe 08m2;tell compiler w..."

2014-03-15T20:53:24Z

Created page with "For an explanation, see Frequency meter. ===Program listing=== ;2014 Shawn Reeves ;measures a frequency of switches between .1Hz and 50Hz #picaxe 08m2;tell compiler w..."

New page

For an explanation, see [[Frequency meter]].
===Program listing===
;2014 Shawn Reeves
;measures a frequency of switches between .1Hz and 50Hz

#picaxe 08m2;tell compiler which chip

;UNCOMMENT ONLY ONE OF THE FOLLOWING TO ALLOW DISPLAY METHOD
;#define useSerial
#define useSPILCD
;#define useShiftLCD

;Define interruptOnHigh if pin goes high when switch on, else comment out
;#define interruptOnHigh

symbol switchPin = C.3
symbol clockPin = C.1;idle low, clock on rise, wait for falling to load next bit.
symbol dataPin = C.2;high = on
symbol loadDataPin = C.4;high = load shift register to segs. AKA CSB
symbol interruptPin = %00001000 ;C.3
symbol interruptValue = %00000000 ;interrupt on low
symbol slowbit = bit0 ;track if frequency too low to measure.
symbol counter = b2
symbol byteOut = b3
symbol shiftCounter = b4
#ifdef useSPILCD
symbol RS = C.0;Note this conflicts with serial out, so one or the other!
symbol tenthousands = b8
symbol thousands = b9
symbol hundreds = b10
symbol tens = b11
symbol ones = b12
#endif
symbol counts = w7
symbol mHz = w8
symbol period = w9
symbol loopWord = w10

init:
pause 100
#ifdef useSPILCD
;This routine should initialize the Electronic Assembly DOG-ME-081 8 character LCD display
;use symbol command to assign loadDataPin, RS, dataOut, and SCK to out pins
;assign a byte variable to byteOut and shiftCounter
initDOG:
high loadDataPin
low loadDataPin
low RS
;The following lines from Electronic Assembly's data sheet, with cursor mode altered.
;One might repeat the following command many times to get the attention of the ST7032 driver
let byteOut = %00110000 ;Function Set, 1 line, instruction table 0
gosub shiftout_MSBFirst
pauseus 27;recommended by ST7032 datasheet

let byteOut = %00110001 ;Function Set, 1 line, instruction table 1
gosub shiftout_MSBFirst
pauseus 27;recommended by ST7032 datasheet

let byteOut = %00110001 ;Function Set, 1 line, instruction table 1, repeat request recommended by ST7032 datasheet
gosub shiftout_MSBFirst
pauseus 27;recommended by ST7032 datasheet

let byteOut = %00011100 ;Bias 1/4, 1 line LCD
gosub shiftout_MSBFirst
pauseus 27;recommended by ST7032 datasheet

let byteOut = %01010001 ;Booster off, set contrast C5, C4
gosub shiftout_MSBFirst
pauseus 27;recommended by ST7032 datasheet

let byteOut = %01101010 ;set voltage follower on, gain 2/7
gosub shiftout_MSBFirst
pause 200;recommended by ST7032 datasheet

let byteOut = %01110100 ;set contrast C3, C2, C1
gosub shiftout_MSBFirst
pauseus 27;recommended by ST7032 datasheet

let byteOut = %00001100 ;display on, cursor off, blink cursor position
gosub shiftout_MSBFirst
pauseus 27;recommended by ST7032 datasheet

let byteOut = %00000001 ;clear display, home cursor
gosub shiftout_MSBFirst
pauseus 2

let byteOut = %00000110 ;entry from right to left (or opposite?), no scrolling.
gosub shiftout_MSBFirst
high RS
#endif ;useSPILCD

setint interruptValue, interruptPin

main:
;Breaking 10µs pause into 1µs pauses, since interrupt causes program to go to next line
;;no matter how far pause was in execution.
;the timing overhead for each iteration of the following loop is about 40µs
for loopWord = 2 to 100
pauseus 990 ;in units of 10µs, so this will count every 10 ms, our least significant digit
inc period
next loopWord
pauseus 800 ;adjust down from 10ms to account for display routine(s) below.
inc period
if period > 1000 then ;more than ten seconds have passed.
slowbit = 1
else
slowbit = 0
endif

sendData:
#ifdef useSerial
sertxd (#mHz,"mHz",13,10)
#endif

#ifdef useSPILCD
low RS ;about to issue a command
byteOut = 1 ;clear display and go to first position
gosub shiftout_MSBFirst
high RS ;about to issue data
if slowbit = 0 then
bintoascii mHz, tenthousands, thousands, hundreds, tens, ones
byteOut = tenthousands
gosub shiftout_MSBFirst
byteOut = thousands
gosub shiftout_MSBFirst
byteOut = "."
gosub shiftout_MSBFirst
byteOut = hundreds
gosub shiftout_MSBFirst
byteOut = tens
gosub shiftout_MSBFirst
byteOut = ones
gosub shiftout_MSBFirst
byteOut = "H"
gosub shiftout_MSBFirst
byteOut = "z"
gosub shiftout_MSBFirst
else
byteOut = "-"
gosub shiftout_MSBFirst
byteOut = "-"
gosub shiftout_MSBFirst
endif
#endif ;useSPILCD

goto main

;This subroutine requires byte variables shiftcounter, byteOut; port.pins dataOut, and SCK
;RS pin should be set high or low before, according to whether a command or data is to be sent.
shiftout_MSBFirst:
for shiftCounter = 1 to 8
if byteOut > 127 then ;MSb must be 1
high dataPin
else
low dataPin
endif
;data must be set at least 10ns before clock rises. If overclocking, uncomment the following line:
;pauseus 1
pulsout clockPin,1 ;rising clock edge initiates read of data
byteOut = byteOut * 2 ;Shift the value so we mask the next bit
;data must remain set at least 150ns after clock rises.
pauseus 1 ;wait 10 microseconds.
next shiftCounter
pause 1
return

interrupt:
mHz = 50000 / period
mHz = mHz * 2 ;fingers crossed period was greater than 1.
period = 0
debounce:
pauseus 1990 ;debounce
period = period + 2
if pin3 = 0 then
goto debounce
endif
setint interruptValue, interruptPin
return

[[Category:Electronics]]