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Homeroasters.org » DATALOGGERS - CONTROLLERS - RATE OF RISE METERS » Dataloggers/Controllers/Rate of Rise Meters
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TC4 + Clippard EVP Proportional Valve + EVPD Valve Driver
JimG
slickrock wrote:
1. Higher voltage hovering 10Vdc on OT2 and OT2. I was under the impression that sending to TC4: OT1, 100, would produce a solid 5Vdc. Instead its producing around 11Vdc very near my VIN value from my 12Vdc power supply. Im using Version 4.00 TC4 board - bought it about 9 months ago, but didn't realize that it was an old version, considering that latest version is 5.30 (am I losing any functionality?). Do I need to change some jumper? Do I need to ground-out the AN0 and AN1 analog input pins?

Version 4.00 of the TC4 provided VIN to the two open collector outputs OT1 and OT2. That explains why you are seeing 11VDC.

Version 5.20 provided a jumper which could select VIN or VCC. Beginning with 5.30 only VCC is available on OT1 and OT2.

You could probably cut the PCB trace on the + (anode) side of the S1AB diode and solder a fly wire to the anode of the diode to use VCC instead.

slickrock wrote:
2. At this high PWM, even a low duty of OT1: 001 registers around 9Vdc as measured by the Fluke. Im suspecting that the fluke is taking the peak and not averaging out the values, so even low duties register as high. Again, it would be nice to see the actual waveform.


The colon is not one of the delimiter options supported by the firmware. Your choices are space, semicolon, comma, or equals sign. Probably this command is not being correctly understood by the firmware.

slickrock wrote:
On another note, is there a way to output to Artisan the OT1 output value when the PID mode is working?


Yes, the current trunk version of the aArtisan.ino code does this now. Since this is a new feature that Marko and I just implemented, I don't know if there is a released version of Artisan that also supports it.

Jim
 
www.pidkits.com
slickrock
JimG wrote:
Version 4.00 of the TC4 provided VIN to the two open collector outputs OT1 and OT2. That explains why you are seeing 11VDC.

You could probably cut the PCB trace on the + (anode) side of the S1AB diode and solder a fly wire to the anode of the diode to use VCC instead.

The colon is not one of the delimiter options supported by the firmware.

Yes, the current trunk version of the aArtisan.ino code does this now. Since this is a new feature that Marko and I just implemented, I don't know if there is a released version of Artisan that also supports it.

Hmm, didnt quite realize how far back the board version was, in that Im basically stuck with VIN. Good news, though, is that the surgery you mentioned above is not required since the EVPD driver accepts 10V command input as a jumper setting. If that doesnt work Ill power the EVPD and TC4 on different voltages (12V and 5V, respectively).

Regarding colon delimiters, what I wrote was a typo, since I was indeed using commas to set values.

Good to know that the feature is being worked on. How is it invoked from aArtisan?

As always, your responses are much appreciated.
 
JimG
slickrock wrote:

Good to know that the feature is being worked on. How is it invoked from aArtisan?


When PID control is active, the new aArtisan will automagically tack on heater output, fan output, and SV after reporting the temperature readings on all active channels.

Jim
 
www.pidkits.com
slickrock
JimG wrote:
Version 4.00 of the TC4 provided VIN to the two open collector outputs OT1 and OT2. That explains why you are seeing 11VDC.

Jim, I think I know at least one of the reasons why you moved OT1 and OT2 to 5VDC instead of VIN. I accidentally shorted out OT1 with a dangling tester clip on OT1 + to ground. I noticed this indirectly when I touched the UNO board it was extremely hot. Now, I'm just getting full 12VDC VIN on OT1 and OT2, no matter what I set the PWM to (note that other functions, such as READ and CHAN work correctly, and Im still getting 12VDC on VIN after the UNO cooled down). Did I basically just fry Q1 and Q2 ? Not having a oscilloscope, how can I test the extent of the damage? Not having the onboard LEDS on V4.0 of the board provides less instrumentation.

Good news is that DIO9 and DIO10 PWM settings work correctly. In fact, my voltmeter shows perfectly correct proportional voltage ranges from these pins that directly correspond to the PWM setting which was never the case on OT1/OT2, which had showed a skewed range like:
PWM 0 : 0.0V
PWM 1: 9.25V
PWM 10: 10.5V
PWM 50: 11.85V
PWM 100: 11.93V

Im thinking Q1 and Q2 that are soldered on my board were only meant for 5VDC rather the 12VDC they were working off of previously.
 
slickrock
Turn of events... just got everything working. Dropped VIN down to 5VDC and transistors seem to work now, though they have same skewed voltages as described above, but at a 4.0V max when the PWM is at 100. I suspect that the transistors don't work well when PWM frequency is that high (2Khz+) . Instead, if I skip using OT1 and drive the EVPD driver directly by the DI09, everything works! Now I can finally get to calibrating the flame settings and PID values.

Thanks for all the help.
 
JimG
There are small voltage drops across the diode and through the transistors. This drops the voltage down from the original 5VDC.

Going directly from the Arduino pins is the right way to go for this application since the output current requirements are minimal.

My thinking on the design for OT1 and OT2 was to provide a couple of outputs with a higher current potential (they are each good for probably 200mA) than the MCU pins. For your application you don't need that.

Jim
 
www.pidkits.com
PhilH
Hi Joel

I have been following your thread with interest
Could you please advise how/where you edited the aArtisan sketch to get the PID to output PWM @ 2khz to DI09

thanks in advance

Phil
 
greencardigan
JimG wrote:
I am not sure how much work it would be to recode the PWM frequency of IO3 to be 2k or higher in aArtisanQ_PID. But probably way more work than soldering a few lead wires to make a low pass filter ThumbsUp

Jim

It took a few years but it's done ThumbsUp

Just needs testing. http://forum.home...post_59700
 
ChrisR
I followed Joel's journey to upgrade his North roaster on the home-barista and started on the same journey to upgrade my BC-5 roaster. The only difference is that I did not construct a bypass for the gas line. Currently, the proportional valve is in series with the gas line.
I have one question/suggestion on the software. Is there a way to write the maximum value to the PWM register so IO3 outputs 5V (PWM wise) via Artisan? This would completely open the proportional valve.
The reason I asked is that i would like to be able to run the roaster in either manual or computer control mode. If I can set the IO3 to max value, the proportional valve would be completely open and I could run the roater in manual mode.
I don't know the aArtisanQ_PID software well enough to do this.
My idea would be that if "Control" mode is not set in Artisan, the PWM register that drives IO3 ould be set to max value. If "Control" mode is set, then the PWM register would be driven based on PID calculated values.
 
greencardigan
You could use a button in Artisan to send a IO3,100 serial command to the TC4. That will set the IO3 output to 100%.

Alternatively you could set up a slider in Artisan and just move it to the 100% position.
 
ChrisR
Awesome
 
Chert
I too have been following this with interest. Thanks to all of you who have posted some experience / progress with it.

When I wish to use a TC4 to control the DC fan by IO3, I am thrilled to see I can use a different pin for the EVPD1 valve controller.
 
ChrisR
Has anybody been able to run their gas roaster using the settings slickrock mentioned at the beginning of the thread? I tried his parts combination (except i used the DVP proportional valve) and could not emulate his success.

I'm also contemplating of going to a stepper controlled proportional valve as it has almost no hysteresis. However, the driver for that valve requires 2 inputs:
1. Step input
2. Direction input

I wonder how difficult it would be to do that with a TC4 board, maybe comparing the previous PWM count to the current PWM count to set direction and use the difference to calculate steps.
Here is some general information

Step: This input is tied high with a 20K Ohm resistor on the driver.
Each rising edge of this input will cause the stepper driver to advance one step in the direction specified by the DIR input. The step input must be high for at least 1 microsecond, and low for at least 1 microsecond.

DIR: This input is tied high with a 20K Ohm resistor on the driver. When a step pulse is received, the driver chip references this input to determine which direction to take the step. When high, the motor will turn counter-clockwise, and when low, the motor will turn clockwise
Edited by ChrisR on 06-07-2018 17:44
 
btreichel
I played with an uno and a $5 stepper board for this purpose; in case I wanted to go that method. Works fine, the Arduino stepper libs handle all the issues.
 
ChrisR
btreichel wrote:

I played with an uno and a $5 stepper board for this purpose; in case I wanted to go that method. Works fine, the Arduino stepper libs handle all the issues.

Hm. I’m curious now. Did you manage to drive the valve?
 
btreichel
Didn't attach it to the needle valve, but just shaft to shaft coupling, and something to hold the steeper from moving.
 
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