Bigtreetech SKR 1.4 Turbo with Thermocouple I'm finally getting around to upgrading my motherboard to a BTT SKR 1.4 Turbo board I've had laying around for a couple years. Seems something malfunctioned with my MKS-Gen-L board, so I need to upgrade ASAP. Everything I've seen looks pretty straightforward except for one thing. I have a Type K thermocouple using an E3D thermocouple board v1.0 which is based on the AD595 chip. I cannot find any information on how to hook this up to the SKR board. I really just need a spare analog input that I can configure in Marlin to read the temp. I've got plenty of sources for providing the 5V and GND, but I need a pin to read the value. Some people talk about using the EXP1 pins, but I have an LCD display that's going to be using the EXP1 and EXP2 connectors. Looking at the schematic for the board, it looks like possibly on the TFT connector, there are 2 pins (0.2, 0.3) which on the LPC1769 chip are labeled as "P0.2/TXD0/AD0.7" and "P0.3/RXD0/AD0.6". I'm guessing that any of the "AD0.x" pins are analog pins. Does anyone know if one of those will work? And since that connector has +5V and GND pins as well, would those analog pins accept a max of 5V input? The E3D board needs 5V input and I think it probably outputs up to 5V as well. This seems to be my only stumbling block in getting this up and running, so any help would be appreciated. https://reprap.org/forum/read.php?13,889115,889115#msg-889115 Wed, 22 Apr 2026 14:53:33 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?13,889115,896572#msg-896572 Re: Bigtreetech SKR 1.4 Turbo with Thermocouple https://reprap.org/forum/read.php?13,889115,896572#msg-896572
Quote
BlakeUnderwood
Quote
brucehvn
Ok, I gave up on trying to get the AD595 board working. I had a AD8495 board laying around I had forgotten about, but it turns out it appears it was bad as I could not get the proper readings from it, even just testing the ambient temperature without it being connected to the printer.

I broke down and bought a MAX31855 board. I have a configuration that I believe is working with that except it causes me to lose the ability to see my SKR card as a USB device on my print server so I can copy the firmware easily which with as many changes as I'm making to the firmware right now is a big deal.
I've been experimenting with various op-amps for my DIY 3D printer controller, and one challenge has always been finding reliable low-power, high-precision options for signal processing. I recently came across the MCP602T-I/SN, which offers low bias current and rail-to-rail output—perfect for precision applications. I sourced it from Ovaga, where they provide detailed specs and availability. It has significantly improved signal integrity in my setup. Has anyone else used this op-amp in their 3D printing projects? Would love to hear your thoughts!
FIrst I had the MAX board hooked to the SPI header on the board. I used pin 0.26 as the CS pin and the SCLK and MISO pins on the header. This didn't work until I set:
#define SDCARD_CONNECTION ONBOARD
Which then caused my ambient temperature to show up correctly, but I lost my USB functionality for my SD card and I could not use the LCD's SD card slot (reprap full graphic discount controller).

I then used the same pins, but defined the MISO and SCLK in configuration_adv.h which according to the comments should throw it into software SPI mode. I set the SDCARD_CONNECTION to LCD and I still was reading a temperature, and I could see the SD card on the LCD with all my GCode files, but still no USB support for the firmware SD Card.

Currently, I'm trying to use the SPI pins on the unused E1 driver slot, but that doesn't seem to work at all. Printer gives an immediate MINTEMP error and halts.

So, I'm confused about a few things. If I want to use Software SPI for the temperature probe, can I specify any open pins, or do they have to be ones designated for SCLK and MISO? I know I can specify any pins for the CS pin.

On this particular board, it looks to me like there are 2 hardware SPI ports surfaced at the SPI header and the EXP connectors where the LCD is attached. The ones in the printer driver pins aren't designated in the processor datasheet as actual SPI pins, but somehow get used as that on the board. Am I correct on those things?

I had the same problem.

How is everything now?]]> RobertEdgar Controllers Tue, 25 Feb 2025 01:05:07 -0500 https://reprap.org/forum/read.php?13,889115,896515#msg-896515 Re: Bigtreetech SKR 1.4 Turbo with Thermocouple https://reprap.org/forum/read.php?13,889115,896515#msg-896515
Quote
brucehvn
Ok, I gave up on trying to get the AD595 board working. I had a AD8495 board laying around I had forgotten about, but it turns out it appears it was bad as I could not get the proper readings from it, even just testing the ambient temperature without it being connected to the printer.

I broke down and bought a MAX31855 board. I have a configuration that I believe is working with that except it causes me to lose the ability to see my SKR card as a USB device on my print server so I can copy the firmware easily which with as many changes as I'm making to the firmware right now is a big deal.

FIrst I had the MAX board hooked to the SPI header on the board. I used pin 0.26 as the CS pin and the SCLK and MISO pins on the header. This didn't work until I set:
#define SDCARD_CONNECTION ONBOARD
Which then caused my ambient temperature to show up correctly, but I lost my USB functionality for my SD card and I could not use the LCD's SD card slot (reprap full graphic discount controller).

I then used the same pins, but defined the MISO and SCLK in configuration_adv.h which according to the comments should throw it into software SPI mode. I set the SDCARD_CONNECTION to LCD and I still was reading a temperature, and I could see the SD card on the LCD with all my GCode files, but still no USB support for the firmware SD Card.

Currently, I'm trying to use the SPI pins on the unused E1 driver slot, but that doesn't seem to work at all. Printer gives an immediate MINTEMP error and halts.

So, I'm confused about a few things. If I want to use Software SPI for the temperature probe, can I specify any open pins, or do they have to be ones designated for SCLK and MISO? I know I can specify any pins for the CS pin.

On this particular board, it looks to me like there are 2 hardware SPI ports surfaced at the SPI header and the EXP connectors where the LCD is attached. The ones in the printer driver pins aren't designated in the processor datasheet as actual SPI pins, but somehow get used as that on the board. Am I correct on those things?

I had the same problem.]]> BlakeUnderwood Controllers Mon, 10 Feb 2025 01:03:50 -0500 https://reprap.org/forum/read.php?13,889115,889163#msg-889163 Re: Bigtreetech SKR 1.4 Turbo with Thermocouple https://reprap.org/forum/read.php?13,889115,889163#msg-889163
I broke down and bought a MAX31855 board. I have a configuration that I believe is working with that except it causes me to lose the ability to see my SKR card as a USB device on my print server so I can copy the firmware easily which with as many changes as I'm making to the firmware right now is a big deal.

FIrst I had the MAX board hooked to the SPI header on the board. I used pin 0.26 as the CS pin and the SCLK and MISO pins on the header. This didn't work until I set:
#define SDCARD_CONNECTION ONBOARD
Which then caused my ambient temperature to show up correctly, but I lost my USB functionality for my SD card and I could not use the LCD's SD card slot (reprap full graphic discount controller).

I then used the same pins, but defined the MISO and SCLK in configuration_adv.h which according to the comments should throw it into software SPI mode. I set the SDCARD_CONNECTION to LCD and I still was reading a temperature, and I could see the SD card on the LCD with all my GCode files, but still no USB support for the firmware SD Card.

Currently, I'm trying to use the SPI pins on the unused E1 driver slot, but that doesn't seem to work at all. Printer gives an immediate MINTEMP error and halts.

So, I'm confused about a few things. If I want to use Software SPI for the temperature probe, can I specify any open pins, or do they have to be ones designated for SCLK and MISO? I know I can specify any pins for the CS pin.

On this particular board, it looks to me like there are 2 hardware SPI ports surfaced at the SPI header and the EXP connectors where the LCD is attached. The ones in the printer driver pins aren't designated in the processor datasheet as actual SPI pins, but somehow get used as that on the board. Am I correct on those things?]]> brucehvn Controllers Thu, 21 Apr 2022 16:36:04 -0400 https://reprap.org/forum/read.php?13,889115,889115#msg-889115 Bigtreetech SKR 1.4 Turbo with Thermocouple https://reprap.org/forum/read.php?13,889115,889115#msg-889115
Looking at the schematic for the board, it looks like possibly on the TFT connector, there are 2 pins (0.2, 0.3) which on the LPC1769 chip are labeled as "P0.2/TXD0/AD0.7" and "P0.3/RXD0/AD0.6". I'm guessing that any of the "AD0.x" pins are analog pins. Does anyone know if one of those will work? And since that connector has +5V and GND pins as well, would those analog pins accept a max of 5V input? The E3D board needs 5V input and I think it probably outputs up to 5V as well.

This seems to be my only stumbling block in getting this up and running, so any help would be appreciated.]]> brucehvn Controllers Sun, 17 Apr 2022 09:33:58 -0400