-
On the picture with the oscilloscope you were connecting the LCR meter directly to the BNC ? Or through a probe ? A 10X or 1X probe ? Because something does not seem right... In 10X the input capacitance should be ~15pF and ~90pF in 1X... Or your meter is indicating 35pF... What does it show when using 1Khz test frequency ? Or 10 Khz ? I mean, the input capacitance of the scope may vary with frequency, but not that much...
About the buttons I think there are 2 options... Of course, it the FW works... You can either live with it, or cut the rubber on the back as a matrix with all the individual buttons and rearrange them in the case... -
Sorry valentinc, that was connected through lots of cabling I had attached to the scope, here you have shots with the osc probe directly to the terminals.
1kHz:
10kHz:
100kHz:
-
Then it means that the only possible calibration data in the EEPROM are the parasitic capacitance, resistance and inductance that are stored when press CLEAR... And if so I'll live with it... It's no big deal to press CLEAR at every turn on... Considering the TH2822C price...
I didn't understand exactly... When you power the meter on with the modified EEPROM, it boots at 100 Khz... And then if you press the FREQ button what happens ? I have the TH2822 (so only 1 Khz)... That means that if I want to switch between 10 Khz and 100 Khz I have to rewrite the EEPROM ? Because that is a real pain...
Because I want to be able to use both 10 and 100 Khz modes... not just the 100 Khz...
-
Then it means that the only possible calibration data in the EEPROM are the parasitic capacitance, resistance and inductance that are stored when press CLEAR... And if so I'll live with it... It's no big deal to press CLEAR at every turn on... Considering the TH2822C price...
It looks like that, but I have no way to confirm it. I tried several capacitors and inductors (the best ones I could get my hand on) and got very close results in 10kHz and 100kHz (after a CLEAR open and CLEAR short process).I didn't understand exactly... When you power the meter on with the modified EEPROM, it boots at 100 Khz... And then if you press the FREQ button what happens ? I have the TH2822 (so only 1 Khz)... That means that if I want to switch between 10 Khz and 100 Khz I have to rewrite the EEPROM ? Because that is a real pain...
In the case of your model ask vtl for details, he got the same one. What I understood, he could only get 10kHz or 100kHz on power up, when pressing FREQ button it would go back to 100Hz in both cases. However a more sophisticated hack using a EEPROM with a "page select" pin (if they exist) could work to select 10kHz power up or 100kHz power up.
I have faith that there's a magic word on the first 2 bytes of the eeprom that will copy the model information from the EEPROM to the MCU, and maybe perform some autocal process to write to EEPROM those data that I think is the default CLEAR open and CLEAR short for each frequency.
I am not very knowledgeable in the measurement process but I think it relies on the theta between voltage and current to determine if it's a cap or an inductor, and it's value. So the real "calibration" would be a timing accuracy issue I think. But again, I'm no one to assume that.
By now I've stopped researching any further hack, couldn't find anything else, but I'm looking forward to get some time to continue searching for a way to do it.
What I did to my meter is write to the eeprom the power up settings I like, solder it and have the WP pin high (write protected) so by accident I could not rewrite it by going to the UTIL menu. It works without problems. -
I bought a TH2822A on eBay for under $190 shipped (USA)
I plan on writing the following to the EEPROM when I get it
Offset 0x54:
0x0F 100kHz power up setting
Offset 0x3F8:
2-byte header 0xA5 0x5A
8-byte data (leave as empty 0xFF?)
2-byte header
8-byte data (leave as empty 0xFF?)
2-byte header
8-byte data (leave as empty 0xFF?)
Offset 0x802:
2-byte header
8-byte data (leave as empty 0xFF?)
2-byte header
8-byte data (leave as empty 0xFF?)
2-byte header
8-byte data (leave as empty 0xFF?)
Offset 0xBF8:
2-byte header
8-byte data (leave as empty 0xFF?)
2-byte header
8-byte data (leave as empty 0xFF?)
2-byte header
8-byte data (leave as empty 0xFF?)
2-byte header
8-byte data (leave as empty 0xFF?)
2-byte header
8-byte data (leave as empty 0xFF?)
*header 0xA5 0x5A
I eventually plan on reading the firmware and finding what enables the 100kHz frequency from the enumeration. Thanks for all the info guys.
I think the battery charger wouldn't be to hard to add, I would need a photo of the other side of the TH2822C board for the component list.
-Frank
PS First post but I've been watching the videos and reading the forum for awhile. -
At a first look the boards look identical (my TH2822 and your TH2822A). The only difference is on the TH2822C, which has additional circuitry for charging the 9V Ni-Mh battery, which ours don't have... I'll investigate further and let you know what I'll find.
Now the problem is I can't find the firmware update for the BK Precision 879B on their website...
If you can find the firmware update file for the BK, please let me know...
The firmware update files for the BK
http://kb.bkprecision.com/getattachment.php?data=MTgyfHYyXzFfdXBkM18wLnppcA%3D%3D
http://kb.bkprecision.com/getattachment.php?data=MTgyfHYyXzFfdXBkMl8wLnppcA%3D%3D -
I2C> (1)
Searching I2C address space. Found devices at:
I2C> (2)
Sniffer
Any key to exit
[[][][[0xA0+0x00+0x40+0xA5+][0xA0+0x00+0x41+0x5A+][0xA0+0x00+0x42+0x00+][0xA0+0x
00+0x43+0x01+][0xA0+0x00+0x44+0x01+][0xA0+0x00+0x45+0x00+][0xA0+0x00+0x46+0x00+]
[0xA0+0x00+0x47+0x00+][0xA0+0x00+0x50+0xA5+][0xA0+0x00+0x51+0x5A+][0xA0+0x00+0x5
2+0x01+][0xA0+0x00+0x53+0x11+][0xA0+0x00+0x54+0x07+][0xA0+0x00+0x55+0x00+][0xA0+
0x00+0x56+0x00+][0xA0+0x00+0x57+0x00+][0xA0+0x00+0x58+0x00+][0xA0+0x00+0x59+0x00
+][0xA0+0x00+0x5A+0x00+][0xA0+0x00+0x5B+0x00+][0xA0+0x00+0x5C+0x01+][0xA0+0x00+0
x5D+0x00+][0xA0+0x00+0x5E+0x00+][0xA0+0x00+0x5F+0x00+][0xA0+0x00+0x60+0x00+][0xA
0+0x00+0x61+0x00+][0xA0+0x00+0x62+0x00+][0xA0+0x00+0x63+0x00+]
I2C> =0X54
0x54 = 84 = 0b01010100
I2C> [0b01010100 r:1]
I2C START BIT
WRITE: 0x54 NACK
READ: 0xFF
NACK
I2C STOP BIT
I2C>
I2C>
I2C> [0b10100000 0 84 r]
I2C START BIT
WRITE: 0xA0 NACK
WRITE: 0x00 NACK
WRITE: 0x54 NACK
READ: 0xFF
NACK
I2C STOP BIT
I2C>
0X54 should be 0x07, but it returned 0xFF
I want to Write 0x0F at address 0x0054 on EEPROM.
Before doing that, I want to read the current record at address 0x0054, I don't know why it did not work.
Please advice,
Thanks -
Normally lcr meter can't be calibrated
-
I tried using Bus Pirate but with no luck. I can sniff the bus on boot and get the same data as with Logic 16, but I can not talk to the chip. I wonder if somehow the bus is held high- not really an I2C compliant thing if I am not mistaken.
I've tested it on standalone EEPROMs and the ones on an old VGA monitor boards and was able to read them just fine : Basically switch to I2C mode, do a discovery scan (1), then set address to all 0: [0xA0 0 0], followed by a read [0xA1 r:100]
On the above chips it works fine, on the one inside the meter I just get NACks on everything and bus scan returns nothing. Looking at the bus with a logic analyzer probes from my scope, I don't see lines wiggle when bus pirate tries to drive them. Weird
My buspirate unable to talk to the eeprom too..
Have u solved the problem ? please give me some advice
Everything returned 0xFF when I try to read some address.
Method1
I2C> [0b10100000 0 84 r] // Read directly from 0xA0+0x00+0x54
I2C START BIT
WRITE: 0xA0 NACK
WRITE: 0x00 NACK
WRITE: 0x54 NACK
READ: 0xFF
NACK
I2C STOP BIT
I2C>
I2C> [0b10100001 0 84 r] // Read directly from 0xA0+0x00+0x54
I2C START BIT
WRITE: 0xA1 NACK
WRITE: 0x00 NACK
WRITE: 0x54 NACK
READ: 0xFF
NACK
I2C STOP BIT
I2C>
method2
I2C>[0b10100000 0 84 ] //position the read pointer to 0xA0+0x00
I2C> [0b01010100 r:1] //read the values of 0x54 address
I2C START BIT
WRITE: 0x54 NACK
READ: 0xFF
NACK
I2C STOP BIT
I2C>
Method3
I2C> [0xa0 0x00][0x54 r:2]
I2C START BIT
WRITE: 0xA0 NACK
WRITE: 0x00 NACK
I2C STOP BIT
I2C START BIT
WRITE: 0x54 NACK
READ: 0xFF ACK 0xFF
NACK
I2C STOP BIT
I2C>
I2C> [0xa1 0x00][0x54 r:2]
I2C START BIT
WRITE: 0xA1 NACK
WRITE: 0x00 NACK
I2C STOP BIT
I2C START BIT
WRITE: 0x54 NACK
READ: 0xFF ACK 0xFF
NACK
I2C STOP BIT
I2C>
-
I tried using Bus Pirate but with no luck. I can sniff the bus on boot and get the same data as with Logic 16, but I can not talk to the chip. I wonder if somehow the bus is held high- not really an I2C compliant thing if I am not mistaken.
I've tested it on standalone EEPROMs and the ones on an old VGA monitor boards and was able to read them just fine : Basically switch to I2C mode, do a discovery scan (1), then set address to all 0: [0xA0 0 0], followed by a read [0xA1 r:100]
On the above chips it works fine, on the one inside the meter I just get NACks on everything and bus scan returns nothing. Looking at the bus with a logic analyzer probes from my scope, I don't see lines wiggle when bus pirate tries to drive them. Weird
My buspirate unable to talk to the eeprom too..
Have u solved the problem ? please give me some advice
Everything returned 0xFF when I try to read some address.
Method1
I2C> [0b10100000 0 84 r] // Read directly from 0xA0+0x00+0x54
I2C START BIT
WRITE: 0xA0 NACK
WRITE: 0x00 NACK
WRITE: 0x54 NACK
READ: 0xFF
NACK
I2C STOP BIT
I2C>
I2C> [0b10100001 0 84 r] // Read directly from 0xA0+0x00+0x54
I2C START BIT
WRITE: 0xA1 NACK
WRITE: 0x00 NACK
WRITE: 0x54 NACK
READ: 0xFF
NACK
I2C STOP BIT
I2C>
method2
I2C>[0b10100000 0 84 ] //position the read pointer to 0xA0+0x00
I2C> [0b01010100 r:1] //read the values of 0x54 address
I2C START BIT
WRITE: 0x54 NACK
READ: 0xFF
NACK
I2C STOP BIT
I2C>
Method3
I2C> [0xa0 0x00][0x54 r:2]
I2C START BIT
WRITE: 0xA0 NACK
WRITE: 0x00 NACK
I2C STOP BIT
I2C START BIT
WRITE: 0x54 NACK
READ: 0xFF ACK 0xFF
NACK
I2C STOP BIT
I2C>
I2C> [0xa1 0x00][0x54 r:2]
I2C START BIT
WRITE: 0xA1 NACK
WRITE: 0x00 NACK
I2C STOP BIT
I2C START BIT
WRITE: 0x54 NACK
READ: 0xFF ACK 0xFF
NACK
I2C STOP BIT
I2C>
-
The MSP430 is pulling up or down strongly the SCL and SDA lines. You need to desolder it.
-
The MSP430 is pulling up or down strongly the SCL and SDA lines. You need to desolder it.
Thanks for helping and answering....
-
Here's another photo of the TH2822A. It was a nice meter--until I killed it with an undischarged cap. After that, it only reported ERR E02. I'm thinking about getting another, but if I happen to do the same thing again, is there any chance of repairing it, and if so, what would most likely have been damaged?
-
Try to check the continuity of F200, right above the spring that connects to the shield on the back of the case... I'm not sure if it's a polyswitch or a simple SMD fuse... But it's worth measuring it...
-
I try to use I2CEEPROMWIN.c to dump the eeprom with buspirate.
It works but the file format messed up.
Please advice how to fix it?
Thanks
-
I see no problem, how should it be?
-
Try to save it in hex format and open with this software... In demo mode...
https://www.wetransfer.com/downloads/ce391a503aa83e088d0c58c57cac53a520140209025302/725ef2cbf259ea746b7feb03f57787cc20140209025303/fab982 -
Here's another photo of the TH2822A. It was a nice meter--until I killed it with an undischarged cap.
I held back buying a TongHui or other expensive cap meter precisely of this reason. I went with a cheaper noname LC200A. But this meter is surprising accurate. Hurt less if someone forgot the cap is charged in the midst of highly focused work. -
Try to save it in hex format and open with this software... In demo mode...
https://www.wetransfer.com/downloads/ce391a503aa83e088d0c58c57cac53a520140209025302/725ef2cbf259ea746b7feb03f57787cc20140209025303/fab982
Thanks for helping,
I write 0x0F at address 0x0054 on the EEPROM, but when I power on the Th2822A, it's still power up with 1kHz.
Anyway, I will try it again! -
EDITED:
The problem has been solved, It suddenly working now, but I don't know why.
-
It may possible to change something in the eeprom to enable the 100kHz option
https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif
Updated: I changed 0x16 from 0x41 to 0x43, but it didn't work...
-
Any news about a final TH2822A to 2822C conversion?
Did anyone dump the EEPROM of a 2822C?
And did anyone try the 100kHz mini-hack on a BK Precision 879b? -
Hi, can anyone share the software FastAccess for Tonghui LCR meter?
Ok, here is link:
http://www.tonghui.com.cn/cn/upload/Download/20200518171724482.rar
