Quentorres
Quentorres is a entry level board perfect for learning programming born at 2024 Instructors Bootcamp held in León. Originally created by Quentin Bolsée and redesigned by Adrián Torres. It has two versions, one where the XIAO RP2040 soldered directly to the board, and the other where the XIAO is removable using connectors.
The board can be produced using the provided PNG renders and we could personalize it for extra credit. Therefore I modified it by adding flanges and holes to make it easier if we want to mount the board inside an enclosure in the future. Other than that, I also replaced the QT with my initial EP.
Milling PCB
We are using Genmitsu 3018 PRO DIY for our PCB milling. To mount the FR-1 stock, we opted to use a 3d printed PCB holder similar like this. We remix the models to adapt it with the nuts and bolts that we have at hand.
Using the PCB holder instead of using a spoilboard has it's advantages and disadvantage. It's much easier to mount and unmount our stock materials, but we lose a little bit of working area that is required for clamping. Another major issue is because there is nothing underneath the stock material, it could flex when the spindle plunges and might result in the material didn't cut all the way through. But the biggest problem will be that the material alignment is highly unlikely to be flat relative to the spindle.
Luckily there is a heightmap feature in Candle, the control software that came 3018. This feature is really similar to what many 3d printers nowadays achieve a perfect first layer. First we import our .nc file generated by MODS, then we could create a height map by probing our stock material with our drill bit. To do this, you need to have a Z-probe and make a non-permanent modification. For detailed instructions, please refer to this guide. From the generated map, the machine will adjust it's Z position when performing the cut operation and compensate the unevenness of the material.
For the milling process, we choose 0.1 mm 20° v-bit for the traces, and 1/32" 2 flutes end mill for the drilling and cutting.
We generate tabs from MODS to prevent the board from falling off at the end of the cutting operation. Unfortunately the control software crashes midway on the last cutting operation. We are not sure what caused it, it already happened a few times randomly. The computer was being used at the same time while performing the machine is running, so it might be a good idea to have a computer dedicated for controlling the machine.
We recorded the coordinates before performing the operations so it's possible to generate an .nc file just for the last bit of the cutting. However, the operation was almost finished and we could easily cut the last bit using a rotary tool.
After breaking the PCB from the tabs, we sand down the outline where the tabs were using a rotary tool, then sand the copper surface with 800 grid sand paper with water. And lastly we test continuity using a multimeter to check if all the copper traces are isolated from one another, no disconnected trace, and no shorted trace.
Soldering XIAO
First we setup our soldering workspace. We learned that quality equipment will make a huge difference in the process. Initially we try a generic soldering station and find the soldering having a hard time to melt. Then we use my personal soldering iron TS80 by Miniware and the solder instantly liquify when touching the iron.
We prefer our XIAO to be removable, therefore we need to solder the 7 pos pin that come with it. To help the soldering process, we mount the pin on a breadboard, place the XIAO, then solder all the pins on both side.
Once we solder all the pin, we test the board by uploading a program to it. First we need to setup our Arduino IDE so it can recognize XIAO board by following this Seeed Studio guide. Then we use the blinking light example, edit the pin number, adjust the blinking speed, and upload it to the board.
Soldering Quentorres
Next we will be assembling our Quentorres. We collect all the required components and laid it out bellow. Unfortunately we are missing the CONN HDR 7POS 0.1 TIN SMD and CONN HEADER SMD R/A 6POS 2.54MM. SMD components are generally hard to come by in Indonesia and even worse in Bali, so we have to try improvising by modifying an 8 pos through hole header.
Here are some steps for modifying the incompatible components:
- We only need 7 and 6 pos header, so first we pull out the excess pins.
- Then we bend the pins and cut the excess to a reasonable length.
- For the button, we simply need to bend the pins a little outward and cut the pin to match the PCB layout while have the body lay flat on the surface.
Next we add solder to my PCB where the components will be soldered at and use flux generously to help the process. Then we place one component at a time at their respective place, hold it with a tweezer while you remelt the solder. In hindsight, this method is not ideal for normal solder. We should have just tinned one connector for each component and only use a small amount. SMD components are really small, they don't need to much solder to be attached, and by tinning all the connectors, it makes aligning the component much much harder.
For soldering the headers, we use the XIAO board to help align them. This is important to make sure the alignment is correct, otherwise we might not be able to plug the XIAO board later. The fact that we also use a non standard SMD header makes aligning the header even harder.
Murphy's Law
Once the headers are soldered, we should check if the pins soldered on the correct position by doing continuity test again using a multimeter. And of course we find one of the bended pin touching a little bit outside of the connector and could potentially create a short. While trying to rectify the issue, I accidentally knocked the header and it peels off a lot of the copper traces.
Files
