Rosscopico0 wrote:Hi Greg!,

I plan to do the mods in a few stages.
Currently the first one is the brew boiler PID (since the original brew boiler thermostat was damaged during removal).

Im wondering with the Piero caps mod, since I will be later replacing a lot (possibly all) of the control systems, if it is worthwhile converting the machine to an EE & doing the EE piero cap mod (Im assuming I will need EE group heads?)

I'm actually a fan of the auto machines once the group solenoid and flowmeter get moved to the group cap. I program the dosing so that one of the keys does a screen-clearing flush, and I have another set to run as a normal auto. The advantage of the automated screen flush is that you don't have to pay attention to it when you're in a hurry. I see no reason to revert back to EE config once the flaws of the Linea AV are corrected by the Pierro caps.

-Greg

Hi guys,

it's going to get technical, so all you coffee purists look away.

What's your programming language of choice? ASM? C? I'm curious because ASM will give you the ability to control everything nicely time-wise as you can easily calculate how much time each function takes. On the other hand C is easier to use for math functions, which is important if you want to do lots of calcs. Are you planning to implement a PID, or something else for control?

Dunno if there's a screw on the LM groups, but on my Elektra I used that to connect the PT straight above the dispersion block:



PWM output works well for pump control and I have to say that the 0-5VDC on the TMFR is actually not that stupid, as 5V is the standard in uC, so you don't need any amps/additional elements to get 0-24VDC, just drive it straight from the output pin like here:

http://www.flickr.com/photos/tompjagiello/4289252148/

[I'm not sure how to put an embed version here]

One thing you have to keep in mind is that the pump is a bit of a b**ch to control. There's a 3-4s response lag in the initial phase, when the basket is filled with water, afterwards it all starts to react a bit faster. This means that if you start with a high update rate for the controller you will get huge overshoot. Also when messing about with a breadboard there's quite a lot of noise and a voltage signal might not like that:



Regards,
dsc.

If you dont want to cut a hole in the front for the PID let me know. I have some old brackets that old the Temp Controller and the solid stat relay laying around. I am trying to clean up my basement for an office and need to get rid of some stuff anyway (I am kind of a hoarder of parts..........). Here are a couple of things that I have done for pressure profiling:

1 - Pressure transducers are expensive but you can find some good one on ebay for around $10. If you are making a product for sale they usually end up costing a bit too much to pass to the consumer.

2 - I do have a transducer that I did some experiments with. Then i applied what I learned to some pre-programmed profiles. I have achieved pretty good results thus far. If you want to reduce the variability, program a pretty long "Pre-infusion (or ramp up) time. Maybe 5-10 seconds. The results seem to make the coffee a bit more forgiving and reduces the impact of tamping, grinding, and believe it or not, coffee freshness.

I am extremely interested in your project! I am doing almost the same thing except with different parts. I too am using a ATMega based system so our stuff is pretty similar.

For the question of programming language, I prefer C. In the end when I want the smallest amount of code so I can us a smaller chip I translate to ASM. But for most applications I like C. Also the C code is somewhat transferable between different micros. So, if you want to share code it is the way to go.

BillC

Hi Bill,

1 - Pressure transducers are expensive but you can find some good one on ebay for around $10. If you are making a product for sale they usually end up costing a bit too much to pass to the consumer.

Ditto, I got mine for 10$ of ebay and it's in good condition, it was probably pulled off some project and not needed anymore (actually quite a lot of stuff gets thrown away this way).

C gets translated to ASM anyway before it gets loaded, it's simply harder to calculate how much each function takes, but I agree it's probably faster to use C.

Regards,
dsc.

dsc wrote:What's your programming language of choice? ASM? C? I'm curious because ASM will give you the ability to control everything nicely time-wise as you can easily calculate how much time each function takes. On the other hand C is easier to use for math functions, which is important if you want to do lots of calcs.

I tend to use C for most of the heavy lifting in the main body of my code. If I run into sections of code that need tighter timing I will usually use one of the hardware timer/counters to trigger an ISR with just the speed critical code.

If that does not get me out of the woods on timing I am not above moving onto a 32bit uC core as these are low volume projects and a dollar or two for the extra muscle to avoid ASM is not going to break the budget. Clear, easy to read, portable code is worth it.

Now days I tend to use the Microchip PIC family of controllers as my first choice, the newer members with USB are quite nice.

-Cecil

Hey guys,
I like Greg's point about keeping the AV setup with the Piero caps, so Ill prob get some Cronos keypads as well.
So while Im saving up for my Piero caps, Ill continue working on the profiling setup, gives me some time.

Dsc, I am writing in C, since I am using an Arduino board, which uses the Atmel AVR microcontroller.
I havent done programming for quite some time, so Im back on a steep learning curve.
So far I have just written a small program that outputs a PWM signal to a motor based on the voltage drop across a potentiometer. I figure its based to take small steps towards my ideal setup.
Next step is to try writing ramp rates, later will be S curves, so if anyone has suggestions, Im all ears!

Bill, I will happily take one of those brackets off your hands, I dont suppose you have some AV Piero caps laying about??

Ross: There is a nice book for the ATmel AVR Butteryfly, (a proto board with LCD, switch inputs, piezo buzzer, temperature, I/O pins, etc) by Joe Pardue called "C Programming for Microcontrollers". I've not managed to make proper time for it but it certainly looks like it could help boot strap you up. It uses the free WinAVR Compiler.

A colleague of mine also used an Arduino board, but he mentioned that some of the build in routines are fairly slow for I/O. At least you can build stuff quickly and then re-code the slow stuff in assembler as needed. I'm pretty impressed with what you can do with a micro-controller now a days.

Mark

Sounds good Mark, Im am ordering one now!

Rosscopico0 wrote:Sounds good Mark, Im am ordering one now!

Digikey has the Atmel AVR Butterfly board for $20. There is also the ECROS AVR carrier board for another $20 that makes it a lot like an Arduino setup.

Mark

Thanks Mark,
Im also looking at the PIC16F627A. I should be able to control the more critical timing cycles with it.
Im going to check with a engineer friend of mine hopefully today.