Ge 6 with Heat bed and seven switch

Hi,
I want to add a 12 V heat bed to my Gen 6 electronic.In the documentation it is mentioned that Traumflugs seven switch can be conected to the Gen 6.
Does anybody has done this and can tell me where to conect?

Thanks in advance

Dirk

I wish all those people who did this already whould tell us on _how_ they did it. It's certainly possible, all you need is a digital I/O pin, ideally one with PWM.

What's available on the Gen6 board?

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Hi,
sorry I am not an expert in electronic, but try to do my best:
There are two more unused conectors:
one is named I2C (4 pin Molex) , the other is ICSP 2x3 pins ...
maybe useful information?

Maybe somebody knows how to conect a thermistor as first step?
Best Regards

Dirk

Note: see last paragraph for short answer.

If you wanted to add a heated bed you'll not only need a seven switch, but also an additional thermistor to monitor the bed's temperature.

Thus this is what we need to get off of the board in order to get this to work:

5V+ (for thermistor)
Gnd (for thermistor and Seven Switch)
Analog Input (thermistor)
PWM output (Seven Switch)

Note: PWM stands for Pulse Width Modulation. Its a way for digital electronics to simulate an analoge output by pulsing on and off quickly.

Looking at the schematic I found here: Gen 6 Circuit in PDF, it appears that there is an unused analoge input available (pin 37 on the Atmega644 see grid 7B). But all the pins that support PWM are currently used. So we'd have to settle for a normal output and use software to simulate the PWM functionallity. You'll have to see if your firmware (or any firmware for that matter) supports software based PWM. I'm still building my first Gen7 board so I haven't gotten into the software side of things yet.

Pins 40 and 41 are both available on the Atmega644 chip. So either one should work.

But without looking at the board, I don't know if there is anywhere you can tap into those pins without soldering wires directly on the leads of the chip its self (this also applies to pin 37).

Both the ICSP and the I2C connectors have both a 5V+ and a Gnd pin so they can be easilly tapped into using a connector on one of them.

The ICSP port is generally only used to program the ATMEGA chip. The I2C is a communication port that's designed to allow microprocessors like the ATMEGA chip to communicate with other devices (like some sensors, displays, or even other microprocessors).

Short answer starts here
So from what I see, you'd need to solder 2 wires very carefully onto the main chip, tap a reference voltage and ground off of either the ICSP port or the I2C port, get an additional 12V off of your power supply, and finally get a firmware that can be configured to simulate PWM. And this also depends if I was looking at the proper schematic for your board.

Edited 1 time(s). Last edit at 05/13/2013 03:23AM by Partier SP.

Most firmwares don't do PWM on the heated bed anyways. IIRC, Teacup is the only one.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Hi,
and thank you for your real good helping answer. Please let me ask for some more details:

I will have a look on my board and I found the pin layout in the Atmega644 documentation. So I think I am able to connect small wires to Pin 37 (for Thermistor) and 41 for PWM output. 5V from
I am not very good in soldering, but I mamaged to change a small SMD Mosfet on my micro helicopter board. 5V from the right pin so I am optimistic, maybe I ask my wife who is better with this small things .
12 V I will employ a sperate power supply
Ground will be conected on both power supplies.

Now my concerns:
Will I have to put in similar resistors than used for the hot end thermistor?

If possible i want to use Teacup (now I have Marlin)
I have the config.h file for my plotter. can I use the Values for Teacup?
How to change and setup the firmware for this new ports and enable PWM?
Or is it OK just to use on / of

I have to install a bootloader first to flash new Firmware

I promize: I will add documantation this on Reprap Wiki , to help guys which are in same situation ...

Regards

Dirk

Dirkkro Wrote:
-------------------------------------------------------
> Hi,
> and thank you for your real good helping answer.
No problem! I've always been interested in electronics and the past year I've finally been able to really start to learn it. Reading Forums and Wikis like these have been a MAJOR help!

> Will I have to put in similar resistors than used
> for the hot end thermistor?
Yes. Now the 4.7k resistor may need to be changed depending on the thermistor you use. From what I've read, that should be good for a 100k thermistor. Also, don't forget to add a capacitor to filter the results a bit. The Gen6 schematics show a 100nF capacitor yet the Gen7 boards use a larger 10uF capacitor. Traumflug do you know why we are using the larger cap? Does it give better filtering or allows for the elimiation of the extra 100k resistor?

And in case you didn't notice, there's a rendering problem with the Gen6 PDF that I linked to earlier. In section E4 there should be a horizontal green trace that joins THERM (pin 32 on the ATMEGA) with R26 and C10. You'll notice similar mistakes anywhere on that drawing where a label overlaps a line.


> If possible i want to use Teacup (now I have
> Marlin)
> I have the config.h file for my plotter. can I
> use the Values for Teacup?
I wouldn't think so but I'm not positive on this. I think I've read that different firmware require different values for what sometimes appears to be the same thing. ie: I thought I read where some firmware packages would ask for the filament diameter some meaning the size extruded out the nozzle and others asking for the diameter entering into the extruder.

Just tonight I got Traumflug's little test firmware uploaded into my new 20Mhz Gen7 v1.5 board to test it out. I'm now going to start looking deeper into firmware configurations. But from what I've read so far I think I'll be leaning towards Teacup too.


> How to change and setup the firmware for this new
> ports and enable PWM?
> Or is it OK just to use on / of
If most firmware don't use PWM for the heated build platform, the I guess its not needed.

>
> I have to install a bootloader first to flash new
> Firmware

Bootloaders should only need to be installed once. After that you should be able to install/modify/change firmwares as often as you like. One of the features of the bootloaders we use on these chips allows us not to require special ISP to reprogram them chips.

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I'm still not too fussy on the idea of soldering directly to the chip. It is very easy to mess it up since the leads are so close together. I had fun trying to solder the MCP2200 down. And its legs are fairly spaced out. If I had to do it again, I'd look for even finer strand of 60/40 solder.