Products > Test Equipment
OWON XDM1041 the unknown multimeter...
bffargo:
Did some testing with a 1041 seeing how easy it would be to hack it into a 1241 with only a couple inexpensive parts.
The internal mains AC->DC power supply is labeled as 5VDC@2A. Actual power consumption measured by feeding in 5VDC from bench supply directly into the output pins of the built in one (not removing it from circuit) are as follows with screen brightness at 25%
Standby: 6.15mA
Boot: 160mA
Run (VDC mode): 100mA
I didn't test any other modes
The mains ground pin is connected all the way through on the negative power rail up until it connects to the meter board at which point it is isolated from the front inputs.
It seems a bypass switch (/ hard power off), a USB>LiIon>500ma(to 2A) charge+inverter board and a decent 18650 should be enough to keep it powered for about 10 hours for little cost and lots of room to put it in the back with the mains board removed.
piit79:
--- Quote from: UniSoft on April 13, 2022, 06:53:38 pm ---
--- Quote from: piit79 on April 12, 2022, 01:21:16 pm ---The ONE thing I'd like to see fixed/patched somehow is the LONG delay on startup - it's very annoying. I wish I could just short-press the power button to put the meter on
--- End quote ---
This can't be changed by firmware...
Power switch is implemented by standalone MCU ATTINY202-SSF...
It is really not hard to write firmware for this MCU. But it cannot be updated via USB/COM.
--- End quote ---
I wanted to share my solution for this issue. Because the simplest one is obviously to replace a tiny 8-bit MCU with a 32-bit dual-core Arm MCU (RP2040) with 2 MB of flash and program it in (Circuit)Python, right? ;)
Anyway, I achieved my goal - now the startup is on single press while the shutdown has a short (~500 ms) delay.
I wanted to re-program the ATtiny202, but I'd have to make a programmer first and I didn't even find the recommended CH340 serial adapter in my junk box. Might still do that later. The program is literally a few lines of code - not sure if there's anything else happening on the MCU, but the startup is controlled by a single I/O pin (PA1; HIGH - DMM starts slowly / LOW - DMM shuts down immediately). The power button is on PA2. I cut the trace going from the power button to the ATtiny202.
The DMM doesn't start all that much faster as there's still a significant delay somewhere down the line, but I like that I can just press the button and know it will start.
mwb1100:
--- Quote from: Alexel on September 06, 2022, 02:49:16 pm ---
--- Quote from: UniSoft on September 06, 2022, 09:06:41 am ---Don't spend time.
This MCU (Cortex-M4) doesn't have that vulnerability.
--- End quote ---
Yes, you are right, I did not pay attention to the fact that the chip marking is GD32F303, not GD32F103...
At the same time, ST-Link reads the chip ID as 0x414, which corresponds to F103, and it would be logical to get 0x422 from our chip (This ID for STM32F303xB/C and STM32F358 devices).
--- End quote ---
Sorry for responding to an oldish post. I think the reason for the ID behavior you're seeing is that the GD32F303 is much more like the STM32F103 than the STM32F303. GD32F303 is basically an STM32F103 clone with a Cortex-M4 instead of a Cortex-M3. The peripheral devices are clones of the STM32F103 peripherals (same register addresses).
ass20:
hi
About versions
version 2.xx have cpu stm32f103 (cortex m3) or clone
version 3.xx have cpu GD32f303 (cortex m4)
gsmart:
Hi dave, i wrote because the same situation as now on my device, different not read at all i have used 4 times now diode is beeping not read volts, and not read resistance at all, fw are 3.1.0 have try to default conf reset but nothing still problem contacted owon with no response and aliexpress buyer protection is 15 day
video attacchment
Thanks for now i hope some one have resolved this issue...
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