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| Amazon Commercial 90DM600 multimeter hacks |
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| sequoia:
Initial analysis of EEPROM access seems to reveal what memory locations in the EEPROM are actually used by the meter. And as expected these locations mostly match to what is documented in DTM0660 datasheet (http://www.kerrywong.com/blog/wp-content/uploads/2016/04/DTM0660DataSheet.pdf) Boot sequence for the meter is as follows (followed by the reads associated with the mode switch): Chipset "main" configuration: --- Code: ---24xx EEPROM: Operations: Sequential random read (addr=F8, 6 bytes): 5A C6 EC 1E 0A 00 Locations: 0xF8 (5A): ??? 0xF9 (C6): configuration data (bitmap) 0xFA (EC): configuration data (bitmap) 0xFB (1E): auto power-off timeout (minutes) 0xFC (0A): backlight timeout (minutes) 0xFD (00): configuration data (bitmap) --- End code --- Chipset full range and range switch configuration: --- Code: ---24xx EEPROM: Operations: Sequential random read (addr=10, 15 bytes): 10 27 0F 27 DE 03 66 66 3D 3D FF 3B 0A FF 40 Locations: 0x10-11 (2710): Default full range (10,000) 0x12-13 (270F): Range switch upper limit (9,999) 0x14-15 (03de): Range switch lower limit (990) 0x16 (66): DC Voltage OL value (102 = 1020V) 0x17 (66): AC Voltage OL value (102 = 1020V) 0x18 (3D): DC Voltage warning threshold (610V) 0x19 (3D): AC Voltage warning threshold (610V) 0x1A (FF): uA Current warning threshold (2550uA or disabled?) 0x1B (3B): mA Current warning threshold (590mA) 0x1C (0A): A Current warning threshold (10A) 0x1D (FF): ??? 0x1E (40): NCV display symbol --- End code --- Unknown data: --- Code: ---24xx EEPROM: Operations: Sequential random read (addr=33, 12 bytes): 04 12 09 6B F8 0A D0 1B 0A 1A 01 0A Locations: 0x33-3E: ??? --- End code --- Temperature measurement calibration data: --- Code: ---24xx EEPROM: Operations: Sequential random read (addr=0B, 5 bytes): 0E 01 E8 D4 03 Locations: 0x0B-0C (010E): Environment temperature (25 C) 0x0D-0F (03D4E8): Environment temperature default ADC value --- End code --- Amplifier parameter and mV calibration adjustment ratios: --- Code: ---24xx EEPROM: Operations: Sequential random read (addr=20, 4 bytes): BB 99 1B 81 Locations: 0x20-21 (99BB): Amplifier parameter 0x22-23 (811B): 500mV calibration adjustment ratio --- End code --- AC mV / V range calibration data: --- Code: ---24xx EEPROM: Operations: Sequential random read (addr=40, 14 bytes): 00 01 00 01 00 07 98 00 64 00 64 00 64 00 Locations: 0x40-41 (0100): AC60mV range noise to be subtracted (input signal is internally amplified) 0x42-43 (0100): AC600mV range noise to be subtracted (input signal is not amplified) 0x44-45 (0700): AC600mV range noise to be subtracted (10M/1.111M resistor divider, amplified) 0x46-47 (0098): AC6V range noise to be subtracted (10M/1.111M resistor divider) 0x48-49 (0064): AC60V range noise to be subtracted (10M/101K resistor divider) 0x4A-4B (0064): AC600V range noise to be subtracted (10M/10K resistor divider) 0x4C-4D (0064): AC1000V range noise to be subtracted (10M/1K resistor divider) --- End code --- Unknown (calibration?) data: --- Code: ---24xx EEPROM: Operations: Sequential random read (addr=4E, 2 bytes): C0 00 Locations: 0x4E-4F: ??? --- End code --- Current calibration data: --- Code: ---24xx EEPROM: Operations: Sequential random read (addr=2A, 6 bytes): 2D 8D AD 8D 95 F7 Locations: 0x2A-2B (8D2D): uA calibration adjustment ratio 0x2C-2D (8DAD): mA calibration adjustment ratio 0x2E-2F (F795): A calibration adjustment ratio --- End code --- Without datasheet for this chipset, it's hard to determine what the "unknown" memory locations do. But comparing EEPROM dumps from different meter using same chipset might reveal something. Especially interesting would be to find out if there is any DMM out there using this same chipset (DM1106EN) that has data logging capability? EEPROM dump from such meter might reveal how to enable it on this meter as well... |
| sequoia:
Looks like serial output may not be easily enabled on this meter or its on different pin than 20.... Flipping bit 1 on EEPROM location 0xFA doesn't seem to enable serial output on this pin: No activity seen on this pin before or after the change (and long press of "REL" button doesn't seem to do anything). Pressing "REL" button however triggers pulses on this pin: I guess having Serial capability easily enabled would have been too good to be true.... Still, great meter for the price (about $30 currently)... |
| Kaluluka:
Hello to everyone! Great work I have to say, but on my brand new 90DM600 hack like above messed up AC and DC Voltage readings! So, for now, I just added only °C temperature to my meter and it works great. Regards to all! Below is ORIGINAL EEPROM from my 90DM600, if someone needs it: |
| coromonadalix:
shhhhhhhhhh loll Amazon will rise their prices :-DD |
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