So, the Integral Non-Linearity is higher than the PSVS2, but because resolution is also higher it is compensated for in software?
Scott's low end non-linearity problem I don't experience on my own PDSV2mini's here.......so some detective work is required.
Ian did a firmware update to 1.01 which I applied to my prototype unit (Ian corrected a problem the math library, as mentioned above), the unit steps by 10uV without missing a beat now, I barely even noticed the original issue anyway but now it is fixed.
You should consider an STM32, not only will it use less power than the AVR, but better software and libraries too
You should consider an STM32, not only will it use less power than the AVR, but better software and libraries too
Something for the future maybe........but what puts me off slightly is the lack of EEprom, albeit they do have EEprom emulation in flash via paged memory or something like that........well, thats as much as I know about STM32 anyways.
Ian.
When you consider that most people would want to keep this device a long time and that the value of the reference to the particular end user increases over time it would be a shame to lose everything to battery leakage. I would extend the battery connector to an external connector as the very first modification and permanently run from external power.
If you keep it normal side up (screen up) it will leak to the bottom of the box, not electronics. Also, it uses rechargeable Li-ion PP3 9V batteries that are not leak prone...
Are you planning to add a remote control?
It has a serial header and you can control it remotely from a PC already much the same as the PDVS2 with an appropriate adaptor......however, I will just be supplying the Ascii protocol used and not a Windows app (well, I might supply an EXE unsupported).
i am not sorry for kicking this topic back alive :-)
wow amazing product you made there Jan, all looks super professional
I really like to see some closeups of the mecanical implementation of the LM399
you say it is under the display ?
and inside 3D printed isolation case ?
the display looks like it can be taken out, so this detail could be revealed,
Are there any long-term stability measurements? For example calibration over several years.
The closest I have is a customer who bought one in Oct. 2019, and then damaged it in Oct. 21 and it was sent to me for repair. A protection diode was replaced and then a full re-cal.
Unfortunately, back in 2019 I didn't produce as full a cal cert as I do now, however, you can see the BIT COUNT changes I had made on the re-cal which will give you some idea.
The closest I have is a customer who bought one in Oct. 2019, and then damaged it in Oct. 21 and it was sent to me for repair. A protection diode was replaced and then a full re-cal.
Unfortunately, back in 2019 I didn't produce as full a cal cert as I do now, however, you can see the BIT COUNT changes I had made on the re-cal which will give you some idea.
Thanks. Comparing a few of the data points, I only see 1-2 counts correction.
If you place a few units in different storage conditions and record their calibration every few months, that could answer the "tba" placeholder for drift in your specifications to increase the (already high) value of your product.
Nitpicking: The certificate specifies 11 digits for voltage output which seems optimistic. Also, including some calibration/accuracy estimation of your 3458A would be helpful.
I wonder if Ian considering to use new 1399 reference in PDVS "3" mini version?
Thanks guys, some good points there.
My automated procedure just logs directly what the 3458A output gave at the time with an NPLC of 100.
Are those numbers reproducable?......no, certainly not at 11 digits, but i figured if thats the numbers the 3458A sees then thats what i record. To be honest, i didnt think twice about it.
I'll look into pulling those digits back on the cal certs on future ones, or maybe adding a statement to the certs.
Thanks,
Ian.
I would be inclined to leave all the digits there, might even help identify minor drifts with the 3458A... there are "only" 5 decimal places on the PDVS2mini, with the last one known to have a little rounding due to DAC conversion, I really wouldn't worry about it, people will only be looking up to the 5th/6th decimal place I expect, the rest is for your own records.
volts10.Text = Format(Val(txtr1aBIG.Text), "#00.0000000")
Hi @IanJ !
Two quick questions.
1. Why aren't you used AD 5791 for DAC?
2. The schematics can be obtained, in order to make an output amplifier that can be driven by PDVS2mini?
Thank you!
The AD5791 is very expensive, and requires a more complicated power supply circuit. Easy to do but affects the BOM.
The schematic diagram is not available I am afraid.
Ian.
is the schematic+fw available for this to homebrew one?
Just saw this:
"The design rights to the PDVS2mini has been SOLD.
Forwarding information for the new manufacturer will be published soon."
why not release this as an open source project?.
why not release this as an open source project?.
why not release this as an open source project?.
Perfect, so <KeyVoltage,0,1.23456> is all it takes in terms of commands(!) wonderful
PDVS2 Serial Protocol (PVDS2 firmware 3.00)
===========================================
INTERFACE = USB (FTDI USB Drivers - http://www.ftdichip/Drivers/VCP.htm)
BAUD: 250k,N,8,1
A simple bi-directional ascii based serial data protocol
Rate = Data from PDVS2 to PC is sent every 110mS
Format to PC:- VR0,0,12345
Format from PC:- <KeyVoltage, 12, 1.23456>
The following details all the data being sent from the PDVS2, and only a partial listing of the data from the PC.
PDVS2 OUTPUTS TO PC:
========================
KV,0, Output Voltage of PDVS2
BV,0, Battery Voltage or DC Input Voltage
BVFM,0, Battery Voltage Feed Mult
OVF,0, Output Voltage Feedback
OVFM,0, Output Voltage Feedback
dacZ,0, DAC Zero Cal
dacS,0, DAC Span Cal
BC,0, Message = DC Input - Charging, DC Input, DC Input - Full, Running on Batteries, Battery Charge high mA!
BLI,0, Message = Status - Low, Status - Ok
Mode,0, Message = Main Menu, Normal, Calibration, Settings, Playback, Ramp
VA0,0, Volts Auto Set[0]
VA1,0, Volts Auto Set[1]
VA2,0, Volts Auto Set[2]
VA3,0, Volts Auto Set[3]
VA4,0, Volts Auto Set[4]
TA0,0, Time Auto Set[0]
TA1,0, Time Auto Set[1]
TA2,0, Time Auto Set[2]
TA3,0, Time Auto Set[3]
TA4,0, Time Auto Set[4]
AC,0, Autocount
AMR,0, Message = Running, Stopped
VR0,0, Volts Ramp Set[0]
VR1,0, Volts Ramp Set[1]
VR2,0, Volts Ramp Set[2]
VR3,0, Volts Ramp Set[3]
VR4,0, Volts Ramp Set[4]
TR0,0, Time Ramp Set[0]
TR1,0, Time Ramp Set[1]
TR2,0, Time Ramp Set[2]
TR3,0, Time Ramp Set[3]
TR4,0, Time Ramp Set[4]
RC,0, Ramp count
RMR,0, Message = Running, Stopped
BMIM,0, Battery Monitor IC Mult
BI,0, Battery current
AL,0, Autoloop
RL,0, Ramploop
SC2,0, Seconds2
dacZ2,0, DAC Zero Cal Dac2
dacS2,0, DAC Span Cal Dac2
VRS,0, Vref Switch
CMS,0, Cal Mode Sub
OUTPUT FROM PC TO PDVS2:
========================
<KeyVoltage,0,1.23456> Voltage requested to output from PDVS2
<VrefSet,0> Vref setting, 0=10v mode, 1=2v mode
Ian Johnston