Products > Test Equipment

RIGOL DP711 and DP712 new 1ch PSU

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ElectronMan:
It is on the side of the upper-board facing the front. The pins have some test pads there.

ElectronMan:
I suppose I should give the obligatory warning for anyone that might want to do this. It's generally not a good idea to hook into live circuits and talk to memory behind the processor's back. My curiosity got the best of me, so I went for it and it worked out.

With that out of the way, a little more detail on what I did. I removed the board with the main CPU on it and found the test pads for the SDA and CLK pins of the i2c FRAM chip. I soldered some wire-wrapping wire ends to the pads and put on a dab of hot glue to eliminate the chances of the ends shorting as the wires moved. I then used some tape for strain relief running the wires out the top of the unit with the case off.

SDA and CLK I ran to the i2C-1 pins on a raspberry pi since it was convenient. I ran ground to the top part of the chassis.

On the pi with i2c enabled, I used the i2cdump command (with PSU powered on) to get the memory pages:


--- Code: ---i2cdump -y 1 83 c
--- End code ---

53 hex (83 decimal) is the one I was interested in. It spits out the entire page.

I created a quick shell script so I could write everything at once and dump the result quickly. The CPU only seems to read from the FRAM every 66 seconds while running, but I wanted to reduce the chances for contention.


--- Code: ---i2cset -y 1 83 0x00 0x02 b
i2cset -y 1 83 0x03 0x08 b
i2cset -y 1 83 0x04 0x71 b
i2cset -y 1 83 0x05 0x02 b
i2cset -y 1 83 0x0a 0x02 b
i2cset -y 1 83 0x13 0x04 b
i2cset -y 1 83 0x14 0x6f b
i2cdump -y 1 83 c
--- End code ---

Once I verified the memory had what I wanted in it, I power cycled the PSU, and my DP712 was "enhanced."

Eric-H:
Thanks for the detailed description!
I did not take the complete unit apart, and was looking at the bottom pcb. Now I know where to look I will give it a try using an arduino.

ElectronMan:
Good Luck! This weekend I might see if I can do anything via serial port commands. I know some devices have allowed writing to memory areas in the past I haven't conducted an exhaustive search of the firmware for undocumented serial commands yet.

Eric-H:
I just enabled all three options on my DP711 by writing to the FRAM via an Arduino   :)
Thanks for the info that made this possible.

Also replaced the bad cap. It was mounted in the wrong polarity!

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