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| Custom Firmware for gpp 4323? |
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| Hydron:
I believe the 10Hz thing is just the rate at which the readings are sent from the channel processor to the UI one - doesn't mean that the ADC is running at that rate. There is a possibility that they're actually running it much faster and using it for a software defined control loop (rather than just generating setpoints for a hardware loop), in which case padding the cap will result in much poorer transient response. If it's only for measurement then yeah that's different and shouldn't be an issue. If you have any more schematics from your reverse engineering effort then that would certainly be of interest, and might clear up the method used. |
| Pr Utser:
It looks like the channel microcontroller handles the OVP and OCP via the same analog inputs as the voltage and current measurement. The low pass filter does affect the OVP and OCP response time. The channel output voltage and current are not affected by the filter (at least not on the short term). I can change the voltage divider ratio to influence the measurement but that does not affect the output voltage or current. So the only valid option is to modify the channel controller firmware. Edit: I found that the channel controller firmware needs no modification. At startup, the UI controller sends an initialization command to all channel controllers. One parameter in this command controls the sampling rate of the channel controller. So by patching the command and intercepting and averaging the samples in the UI firmware, the measurement readouts can be improved. The OVP/OCP handling is processed by the UI controller. Given the claims in the GWInstek brochure (stating that OVP/OCP is implemented in hardware instead of software), I did not expect this. It could have been close to a hardware implementation by letting the channel controllers handle OVP/OCP. The ADC has a feature to compare the conversion result with a preset threshold level and generate an interrupt if the threshold is crossed. This could have been used to implement a near hardware OVP/OCP solution. I see it as a missed opportunity by GWInstek. They shouldn't lie about it in the brochure though. Unfortunately, the brochure is not as "Simply Reliable" as the company's slogan claims to be. |
| Pr Utser:
You can now create your own custom firmware for the GPP-4323 :-/O. See https://www.eevblog.com/forum/projects/firmware-mod-for-gwinstek-gpp-series-lab-bench-power-supply |
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