So now resetting the ports before jumping:
sub_7f00: ; From bootloader
br !llab_7fdb ;7f00 9b db 7f ; Go to failsafe check
lab_7fdb: ; Failsafe check
mov pm7,#0xf0 ;7fdb 13 27 f0 ; Set P7.7-4 as input, P7.3-0 as output
mov pu7,#0xf0 ;7fde 13 37 f0 ; Enable P7.7-4 pullups
mov p7,#0x00 ;7fe1 11 07 00 ; P7.3-0 outputs low
movw ax,#0x0100 ;7fe4 10 00 01 ; Much smaller delay
lab_7fe7:
subw ax,#0x0001 ;7fe7 da 01 00
bnz lab_7fe7 ;7fea bd fb
mov a,p7 ;7fec f0 07 ; Move P7 value into A
mov pm7,#0xff ;7fee 13 27 ff ; Clear port config
mov pu7,#0x00 ;7ff1 13 37 00
bt a.7,lab_7ff8 ;7ff4 31 7e 01 ; test A, bit 7
ret ;7ff7 af ; Return (Button pressed)
lab_7ff8:
br !lab_3015 ;7ff8 9b 15 30 ; Enter app (Not pressed)
Finally loaded the "U1273AX_V301_failsafe_p74.ag" on meter. Meter works fine, no problems at all.
I used DSD Tech SH-U06A to load it this time so I don't have to take apart optical comm and solder in the Rx Tx Gnd pins. See attached photos.
Now, what is the expected operation of this failsafe version?
It's just reading a different input. Try finding which button causes it to go into update mode (Holding while powering on).
Might not be connected to any button, that's why I made the four p77...p74 tests.
So there is NEC uPD78F0547 inside. My Fluke 189 uses Sharp SM6004 chip. No docs, no tools, etc. What was the reason for widely using a Japanese MCUs in the DMMs of the US brands? If there was a shortage of the domestic MCU designs back at that time?
So there is NEC uPD78F0547 inside. My Fluke 189 uses Sharp SM6004 chip. No docs, no tools, etc. What was the reason for widely using a Japanese MCUs in the DMMs of the US brands? If there was a shortage of the domestic MCU designs back at that time?
Maybe those design teams are in Asia, and they naturally gravitate to home-grown mcu's.
US based design teams are perhaps more focussed on bench / high-end gear, where "western" mcu's are common.
Just guessing. Maybe just cost driven.
So there is NEC uPD78F0547 inside. My Fluke 189 uses Sharp SM6004 chip. No docs, no tools, etc. What was the reason for widely using a Japanese MCUs in the DMMs of the US brands? If there was a shortage of the domestic MCU designs back at that time?
Maybe those design teams are in Asia, and they naturally gravitate to home-grown mcu's.
US based design teams are perhaps more focussed on bench / high-end gear, where "western" mcu's are common.
Just guessing. Maybe just cost driven.
I don't know about Fluke. Keysight's handheld multimeters are designed and produced by Escort Instruments, a Taiwanese company acquired by Agilent in 2008.
How to replace the Agilent / Keysight OLED display for just $10!
- Buy the display: Aliexpress (Or search for "SSD1309 8080").
(Attachment Link)
- You might need to install the Prolific drivers. If getting code 10, install the attached drivers.
- Make sure Windows is using them: Open the Device Manager, check those under USB devices/USB serial port and COM ports/USB serial port, replace driver if needed.
- Don't attempt loading a firmware from another model, it'll brick the device! (Not irreversible, see Recovering section below)
Agilent / Keysight U1273A / U1273AX
If your device has firmware version v4.xx it will work straight away, no firmware modification is required!
- Confirmed working!
- Download and extract U1273A(X)_V303_mod.zip.
- Run the updater.
- Original installers from Keysight: U1273A, U1273AX .
Must be v3.01, newer version will check the current firmware and block the update if already in the latest version!
Just change the firmware name to U1273A(X)_V301.AG. (A or AX).
Agilent / Keysight U1253A
- Confirmed working!
- Download and unpack Agilent U1253A Firmware Update V120_mod.zip.
- Run the updater.
Agilent / Keysight U1253B
- Same mod as 1253A, so it should work.
- Download and extract U1253B_V304_1123a_mod.zip.
- Run the updater.
Reverse enginnering details
All the bits & low-level details can be found few posts below.
Recovery
If something goes wrong, it's pretty easy to recover using a usb-serial converter, read the messages starting here.
Great thanks to you guys working on thist project!my meter is now back to live again.
But as a reminder, I think you guys should uploader your work on github or a similar platform and attach a License to it.
I am from China and have already seen someone selling this firmware on the local network.
You can make an optic cable for sure, it is actually quite simple circuitry. Do you by chance have a 3D printer? that would be needed to print out a snap-in head that would align the LEDs of the UART with meter LEDs. I can throw together a printable file and a circuit board quickly if you are interested.
If it is a bit too involved, then what can be done is to use regular FTDI UART usb cable/dongle and connect directly to the meter internal header (which is definitely present in U1273AX on the top right of the board. Not sure where it is in 1253A
No, the internal header is a different port, I don't think it's "talkative"?
In U1273AX port is fully talkative, I did couple of firmware updates from it directly instead of using the optical UART. It was the same port that I used to "unbrick" the meter (with your smart guidance!) when I messed it up, remember?
Are you sure?
I recall you stripped the original cable to unbrick the DMM, accessing rx/tx signals and connecting them to the header.
But that's the only use for it that I remember, the updating was done with the optical cable, right?
Or did you update through the header
here?
I am definitely sure. Later on I even posted that I got a FDTI USB to UART from Amazon which I connected directly and was able to use that connection for uploading of firmware using the stock Keysight/Agilent firmware uploader. It definitely detected the meter and cycled through the update process without problems.
Or did you update through the header here?
Yep, I used it there too.
Thanks Again! I did try today to buy in my country the OLED display and none it's compatible, I need to buy in ebay or in aliexpress then would took one month to arrive.
I can make the IR-USB cable meanwhile , I have several CNC machibes to make the head, I can post results here.
Anybody used another colour than Yellow for the display? It's less readable in white than yellow?
Thanks again for your enormous work, it's a real shame that Keysight not provided this firmware mod.
I personally liked the original yellow color of OLED, also I think DavidAlfa mentioned something about yellow OLEDs having the most time longevity but I might be mistaken on that.
Originally the blue compound on oleds had the lowest livespan * by a lot *.
Not sure nowadays, but probably still the weakest.
I found my U1173B and did a teardown and RE for it. The circuit diagram was not carefully checked and organized so it looks a bit messy, but it should be readable.
Thanks Gamalot, with the pictures I can make an own cable. Somebody try the update with the bluetooth version? Thanks