New to Gen7, not to Microcontrollers Hi, I've mainly been involved with PIC development (etched a few boards) and as I've just built a Foldarap, I decided to have a go at driving it with Gen7 with Marlin firmware. I've redone the design in KiCad (it's what I'm familiar with) and used molex headers everywhere (it makes it easy to manage) and screw terminals for the power (using a 250W fixed 12V power supply). I'm using an ATMega1284P at 20MHz, and I can load a bootloader with my programmer (Avrdude 6 supports using a Pickit2 to program AVR's, awesome!), but I cannot then use the onboard bootloader to program the firmware (I've tried optiboot, Gen7 support bootloaders + others, just refuses to talk - fuses are right, so at a loss there). No big deal, I can use a command line (linux user) and drop the hex file onto the chip without issue. So I've compiled Marlin (best guess) and it talks quite happily to my PC. I suspect there's an issue with the pin configuration though, as it's not driving the hotend (LED doesn't light up) and the bed's permanently live. Is there a guide of any sort out there? I've googled and looked, but not very much information out there. TIA https://reprap.org/forum/read.php?181,265743,265743#msg-265743 Sat, 15 Aug 2026 02:46:18 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?181,265743,268513#msg-268513 Re: New to Gen7, not to Microcontrollers https://reprap.org/forum/read.php?181,265743,268513#msg-268513
[attachment 21317 Heatbed.jpg]

this was plain copperclad FR4, I have a Seno Phenolac applicator that covers the board in a light sensitive chemical, I printed my design onto transparency and developed it as normal - some problems where the covering was uneven, but I was able to get a useful heatbed out of it

Tests with some prints went very well

[attachment 21318 Calibrationprints.jpg]]]> majic79 Next Wave Electronics Working Group Sun, 17 Nov 2013 17:55:33 -0500 https://reprap.org/forum/read.php?181,265743,267337#msg-267337 Re: New to Gen7, not to Microcontrollers https://reprap.org/forum/read.php?181,265743,267337#msg-267337 majic79 Next Wave Electronics Working Group Fri, 15 Nov 2013 05:23:45 -0500 https://reprap.org/forum/read.php?181,265743,267032#msg-267032 Re: New to Gen7, not to Microcontrollers https://reprap.org/forum/read.php?181,265743,267032#msg-267032
Quote

Is there a reason for a lack of fan control pins?

There is no lack, just no dedicated connector. Ideally, always-on fans are connected directly to the power supply, which is turned on and off by software. Controlled fans are connected to the extension board header, typically with a SevenSwitch in between to allow more than 5V and 20 mA.]]> Traumflug Next Wave Electronics Working Group Thu, 14 Nov 2013 14:12:26 -0500 https://reprap.org/forum/read.php?181,265743,266406#msg-266406 Re: New to Gen7, not to Microcontrollers https://reprap.org/forum/read.php?181,265743,266406#msg-266406
Starting to realise the benefit of this machine now, I may have to do a quick hack to the print head so that I can add a dremel to it and mill my hot bed with it :D]]> majic79 Next Wave Electronics Working Group Wed, 13 Nov 2013 10:53:51 -0500 https://reprap.org/forum/read.php?181,265743,266238#msg-266238 Re: New to Gen7, not to Microcontrollers https://reprap.org/forum/read.php?181,265743,266238#msg-266238
Quote

I'm a happy maker

That's what we want to hear :) Glad you got it worked out.]]> Traumflug Next Wave Electronics Working Group Wed, 13 Nov 2013 05:43:48 -0500 https://reprap.org/forum/read.php?181,265743,266071#msg-266071 Re: New to Gen7, not to Microcontrollers https://reprap.org/forum/read.php?181,265743,266071#msg-266071
It works and moves and heats up the head, just a reduced size hotbed to finalise for my foldarap and I'm a happy maker]]> majic79 Next Wave Electronics Working Group Tue, 12 Nov 2013 18:54:51 -0500 https://reprap.org/forum/read.php?181,265743,265978#msg-265978 Re: New to Gen7, not to Microcontrollers https://reprap.org/forum/read.php?181,265743,265978#msg-265978 majic79 Next Wave Electronics Working Group Tue, 12 Nov 2013 14:54:05 -0500 https://reprap.org/forum/read.php?181,265743,265839#msg-265839 Re: New to Gen7, not to Microcontrollers https://reprap.org/forum/read.php?181,265743,265839#msg-265839
I'm primarily a software engineer (hardware is more of a hobby!) and I couldn't identify any issues looking at the pins.h file in marlin firmware (I've used "#define MOTHERBOARD 13" which should select Gen7 V1.4+ configuration and the diagrams I've seen for arduino pin configuration match that of my schematic and board) I'll have a closer look at the pin configuration for 1284p when I get home - I wonder if there's a mismatch somewhere in the code

A question about the resistors driving the pins of the MOSFETs, do they need to be there? I would have thought that a direct connection from the ATMega to the MOSFET control pin with a 10k pulldown would work fine, this way it's never floating and only comes on when voltage is applied? I can do a quick hack to my board and link the pin directly (no resistors to drive the pin) and have a 10k SMD pulldown with ease - but I've not worked with MOSFETs much (I've usually only used BJT's) and don't want to pop them (I have spares, but I've already smoked one MCP2200 when I managed to reverse the polarity of a 7805 - I don't want to waste too much money!)]]> majic79 Next Wave Electronics Working Group Tue, 12 Nov 2013 09:24:26 -0500 https://reprap.org/forum/read.php?181,265743,265817#msg-265817 Re: New to Gen7, not to Microcontrollers https://reprap.org/forum/read.php?181,265743,265817#msg-265817
Regarding your issue, check the voltage on the ATmega pin. If this does change between M104 S0 and M104 S200, you have a short or a missing connection somewhere. Typically, electromagnetic radiation in the environment is sufficient to drive a MOSFET pin, so having the MOSFET open can also mean the gate pin is disconnected.

If the pin doesn't change, it's a Firmware issue (wrong pin configuration) and I'd change forum section and title of the post accordingly.]]> Traumflug Next Wave Electronics Working Group Tue, 12 Nov 2013 08:18:32 -0500 https://reprap.org/forum/read.php?181,265743,265743#msg-265743 New to Gen7, not to Microcontrollers https://reprap.org/forum/read.php?181,265743,265743#msg-265743
I've mainly been involved with PIC development (etched a few boards) and as I've just built a Foldarap, I decided to have a go at driving it with Gen7 with Marlin firmware. I've redone the design in KiCad (it's what I'm familiar with) and used molex headers everywhere (it makes it easy to manage) and screw terminals for the power (using a 250W fixed 12V power supply). I'm using an ATMega1284P at 20MHz, and I can load a bootloader with my programmer (Avrdude 6 supports using a Pickit2 to program AVR's, awesome!), but I cannot then use the onboard bootloader to program the firmware (I've tried optiboot, Gen7 support bootloaders + others, just refuses to talk - fuses are right, so at a loss there). No big deal, I can use a command line (linux user) and drop the hex file onto the chip without issue. So I've compiled Marlin (best guess) and it talks quite happily to my PC. I suspect there's an issue with the pin configuration though, as it's not driving the hotend (LED doesn't light up) and the bed's permanently live. Is there a guide of any sort out there? I've googled and looked, but not very much information out there.

TIA]]> majic79 Next Wave Electronics Working Group Tue, 12 Nov 2013 04:48:07 -0500