40X2 and TUNE

[Aries]

Another oddity with the 40X2 - it seems that the TUNE command does something to the internal clock frequency.

This code tests a piezo sounder by playing a (rather off) sequence of octaves, printing out the counter and the tune-code frequency. Without a PAUSE (or with PAUSE 0) after the TUNE command, the next sertxd is garbled for the first argument, and then reverts. PAUSE for any longer time works correctly. This only happens at em64. It's not a problem as long as one knows, but it is annoying.

#picaxe 40x2
#no_data
#no_table
symbol SoundPin = D.0

symbol RingTone = 0

#terminal 76800
setfreq em64

pause 8000

ptr = RingTone
for b0 = 0 to 255
    lookup b0,(3,$E0,$E2,$E4,$E5,$E7,$E9,$EB,$C0,$C2,$C4,$C5,$C7,$C9,$CB,$D0,$D2,$D4,$D5,$D7,$D9,$DB,$FF),b1
    @ptrinc = b1
    if b1 = $FF then exit
    next b0

    b3 = 0
main:
    b0 = RingTone
    b3 = 1 - b3
    get b0,b1    '    tempo
    for b21 = 0 to 63
        sertxd(13,10,#b0)
        b0 = b0 + 1
        get b0,b2    ' next note
        if b2 = $FF then EndRing
        sertxd(" ... ",#b0," ",#b2," (",#b3,")")
        tune SoundPin,b1,(b2)
        pause b3
        sertxd(" .. ",#b0)
    next b21
EndRing:
    pause 1000
    goto main

and the results:

...
16 ... 17 212 (1) .. 17
17 ... 18 213 (1) .. 18
18 ... 19 215 (1) .. 19
19 ... 20 217 (1) .. 20
20 ... 21 219 (1) .. 21
21
0 ... 1 224 (0)[00][9E]y[97] 1
1 ... 2 226 (0)[00][9E]y[97] 2
2 ... 3 228 (0)[00][9E]y[97] 3
...

 

[Technical]

There are a number of timing critical commands that always run at the default internal frequency regardless on all parts (as they would not work at all at other frequencies). These include command such as irout, readtemp, tune etc.