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JimG wrote:
I'm probably getting ready to expose my ignorance (again), but don't you need to reserve D0 and D1 for talking to a PC over a serial interface?

Jim

JimG wrote:
I think that A2 through A5 are available on your PCB. I think D3, D5, D6, and D11 are also available.

The resistor ladder is a much more manly solution, though

Jim

JimG wrote:
Nice! Looking forward to learning more about how you're making all this magic happen.

BTW, I goofed on the available pins. Pins A4 and A5 are definitely NOT available. They are dedicated to the I2C bus in our designs.

However, A0 through A3 could have been used for the unmanly option.

Jim

allenb wrote way back on 26 August:
Helpful info & links re SMD soldering

Allen

JimG also wrote back on 27 August:
More SMD tips & info

Jim

allenb wrote:
Looks like your making excellent progress Randy.

Good to see the PID side of things working out.

Now, since you probably need to take a break from intense design and testing, here is something to ponder for future optional modes of operation.

Instead of selectable profiles, have a stepped rotary dial allowing the operator to select rate of rise rates at-will during the roast. With that, we could fine tune the contour of the roast while it progresses which would allow real-time interactive roasting without being fully manual. For an example, the asymptote curve Marshall is using around 300F would be easy with this type of control.

For folks liking to roast in more of a hands on approach this would bridge the gap between fully manual and automated.

You could either label the faceplate around the dial with the RoR rates or go fancier with it showing on the LCD.

Allen

randytsuch wrote:

I was thinking of controlling the roast based on ROR and bean temp.
So, you could say for up to 250F bean temp, ROR = 20, then up to 350F ROR = 15, etc.

Randy

Dan wrote:
This project is moving along well! Lots of fits and starts, but a life of its own. I've been trying to keep up, programming is not my thing. I design, build and wire PLC controlled machines, but job out the programming.

From what I can tell, I've not seen an overview or summary, this project and KONA in particular is intended for controlling a hot air roaster, because the profile includes fan speed. Is that true?

If so, I see in the profile program that the fourth line is being used for fan speed, set at percent of full power. From what I can tell, the fan is being controlled with preset speeds but not being set automatically (automatic operation requires a feedback loop).

And, I see that there is a fan overide option for the operator. If an operator must be present to control the fan speed, then ipso facto it negates having the fan being controlled by the controller program in the first place. The whole idea of a controller is so that you don't have to monitor the roast and tend the equipment.

I think there was some discussion early on about using a pressure transducer for fan speed, but these are expensive and the pressure difference between spouting well and not spouting well is minute.

I always thought I'd use an optical sensor for automatic fan control in a hot air roaster. It would be mounted somewhere in the area of the roast chamber where the beans would jump into when spouting, but not at the top. It might need a light source on the opposite wall of the roasting chamber. Then, control the fan speed so that the light from the source is being obscured from the sensor's perspective some proportion of time, say 30% of the time. This makes the fan speed dependent upon spouting height regardless of the bean density before or during the roast.