Advertising Index
Altronics.................................35-38
Blackmagic Design....................... 7
Dave Thompson........................ 111
DigiKey Electronics....................... 3
Emona Instruments.................. IBC
Hare & Forbes............................... 9
Jaycar............................. IFC, 59-62
Keith Rippon Kit Assembly....... 111
Lazer Security........................... 111
LD Electronics........................... 111
LEDsales................................... 111
Microchip Technology.............OBC
Mouser Electronics....................... 4
PMD Way................................... 111
SC Ideal Bridge Rectifiers......... 108
Silicon Chip Back Issues......... 103
Silicon Chip Binders................ 111
Silicon Chip PDFs on USB......... 80
Silicon Chip Shop...................... 95
Silicon Chip Subscriptions........ 81
TME............................................. 11
The Loudspeaker Kit.com.......... 10
Wagner Electronics....................... 8
Notes and Errata
Automatic LQ Meter, July 2024:
a few constructors had problems
with IC1 (OPA2677) oscillating,
making it hot and causing
excessive current to be drawn
from the battery. Some have
solved it by replacing diodes D1
& D2 with some from a different
batch or by adding a 220Ω resistor
in series with diode D1 (see
Mailbag, September 2024, page
10). A better solution is to replace
IC1 with an OPA2890 op amp. If
you bought a kit and have this
problem, contact us to request an
OPA2890.
Next Issue: the November 2024
issue is due on sale in newsagents
by Monday, October 28th. Expect
postal delivery of subscription
copies in Australia between October
25th and November 13th.
112
Silicon Chip
Clock (December 2015 & January 2016;
siliconchip.au/Series/294) and set up
MPLAB X v5.50 and the current XC32
compiler. It appears that Microchip no
longer includes the plib.h, math.h and
string.h headers with the compiler.
Can you tell me what version of
MPLAB and the XC32 compiler you
used when you developed the clock?
The code is in a folder called LED
Clock.X, which suggests that the IDE
was some version of MPLAB X. Starting with v5.35, it wanted to upgrade
the file, so I worked backwards to v4.20
which didn’t.
Having found those headers, I got
a heap of other errors when I tried
to compile the code. I think it might
be better if I use the same version
of the software you did originally.
Some lines in the code that are particular problems are calls to assembler
instructions such as:
asm volatile (“eret”);
There is a similar line with the
“wait” instruction. Do I have to do
something in Project Properties to get
these lines to compile/assemble? The
error message is:
“C:\Program Files (x86)\
Microchip\xc32\v1.31\bin\
xc32-gcc.exe” -x c -c
-mprocessor=32MX170F256B
-ffunction-sections -mips16
-Os -fomit-frame-pointer
-DSHOW_UTC_FEATURE=1 -MMD -MF
build/default/production/
sleep.o.d -o build/default/
production/sleep.o sleep.c
-DXPRJ_default=default
-legacy-libc -mno-float
-G2048
C:\Users\Gjc\AppData\Local\
Temp\cciHwjKm.s:133: Error:
unrecognised opcode `wait’
(G. C., Mount Dandenong, Vic)
● You are right that they are no
longer packaging those older libraries
with XC32. This page on the Microchip
website explains where to get plib.h
and the other headers: siliconchip.au/
link/abyw
It is now a separate download on
the same page where you get the compiler. “math.h” and “string.h” are part
of the standard C library, so we are surprised they are not included with the
compiler. The above download may
include them as well.
The build logs in the software
download package show that the
Australia's electronics magazine
compiler used was XC32 v1.31. It
should be possible to get it to compile with the latest XC32 with some
fiddling (basically downloading and
installing headers), but you are right
that it might be easier to go back to
that earlier version.
We wonder if the “unrecognised
opcode” error is related to the -mips16
option. We suggest you try switching
off the MIPS16 option for that file;
you can do it in the IDE on a file-byfile basis.
MIPS16 is a more compact instruction set, and we used it because the
code wouldn’t fit into the available
flash memory otherwise. However, it
doesn’t seem to include the wait or eret
instructions; those appear to be part
of MIPS32 only. We suspect the compiler used to detect that and switch to
MIPS32 mode to execute those instructions, but it may no longer do that.
The strange thing is that the code
obviously compiled for us back in
2015, even though we were using the
same version of XC32 (v1.31) as you.
Perhaps it has something to do with
the IDE providing the compiler with
a different set of option flags.
Without the MIPS16 flag, the compiled objects will likely be a little
larger, but we don’t think they all need
to be MIPS16 for the software to fit in
the chip. So you might be able to get
away with switching just those problem files back to MIPS32 mode.
Information wanted on
EA project
I am looking for the original article
for the Xenon Strobe Timing Light
project that used a Dolphin torch
for the reflector and housing. I built
one when I was younger. It was published approximately between 1980
and 1982; I seem to remember it was
either in the Electronics Australia or
ETI magazine.
Looking through EA issues between
1979 and 1982, I found the Digital
Tacho/Dwell meter and the Transistor-
Assisted Ignition projects that I built
around the same time, but not the
Strobe. (S. R., via email)
● The only project we can find in
EA or ETI that used a Xenon flash tube
in a Dolphin torch reflector is the Digital Strobe project in EA, March 1986
(starting on page 42). However, it is a
strobe and not a timing light, as it isn’t
triggered by an ignition system. SC
siliconchip.com.au
