To make the experience fit your profile, pick a username and tell us what interests you.
There's a few reasons I'm working on this besides just creating yet another little ARM Cortex-M dev board:
I put together a quick project with the MoonLander for the OSHPark #BringAHack dinner after Maker Faire, which I called the BICORDER. All the code is up on Github. It was a good chance to test out the board - the one annoying thing was not having a base board to adapt it to a 0.1" header for easy breadboarding, so I ended up soldering temporary wires for prototyping then had to remove those to wire it up in the case. I'm still happy with the 2mm pitch for the I/O, I just need to make up an adapter board (I actually have a board already, I just gotta sort out getting the right height headers and standoffs).
So, here's my thoughts for the PC side software:
The idea is to make something cross-platform and easy to use - it would be possible for anyone to download a firmware binary, plug in the board and upload.
Another possibility would be to hack it into the Arduino IDE, which is something JeeLabs worked on a bit: http://jeelabs.org/2015/10/14/arduino-ide-w-lpc824/ - they ran into a problem with using the RTS & DTR signals to trigger the bootloader using an FTDI converter, but I think it should be doable with the CP2110 and some custom bootloader code? I don't know, I've never looked into adding new platforms to Arduino (and I'd rather not use Arduino anyways - ultimately I want this to be a platform for simple, very-low-power applications, and Arduino is far from ideal for that).
Now I just need to learn QT...
I think I've just about finished rev B of the PCB - the main changes I've made are:
I was originally planning on including some sensors on board for a sort of all-in-one "IoT" platform, but I think it's more important to keep the cost down. The EEPROM is a fairly inexpensive part, and I think it's worth the 0ドル.20 or so to add data logging as a core functionality.
I've pushed the latest changes to Github.
One of the big reasons I made this board was to check out the CP2110 HID USB-UART IC. At 1ドル.85 in single quantity (CP2110 from Digi-Key), it pretty much blows the ~4ドル.50 FT232 out of the water price-wise. Also cool is that it is HID based, and therefore doesn't actually require any drivers to communicate with it (Silicon Labs also make the 1ドル.80 CP2104 USB-UART bridge that requires a driver and would be a more direct competitor for the FT232).
Being HID based, the CP2110 doesn't just show up as a serial port when you plug it into your computer, so I've been working on a quick and dirty C library to control it here (using hidapi). My next step will be to use that API to implement the serial ROM bootloader in the LCP824 to program it over USB. In the next hardware revision I'll probably have the reset and ISP entry pins controlled directly by a couple CP2110 GPIO pins, which will allow the programming software to reset the LPC824 into the bootloader itself.
Create an account to leave a comment. Already have an account? Log In.
Yeah, I've gone back and forth on that a bit. I have plans for a more feature-rich board using a fancier NXP cortex-m0 that does have a ROM USB bootloader. But feature creep was creeping, so I decided to start with a minimal board for the LPC824 to keep it real low cost.
I thought about leaving the USB-UART chip off the board for price, but I hate the idea of having a USB port that's just for battery charging, and it's pretty low cost itself.
I figure if anything it's worth it for now just to get the software for the CP2110 together, as it's a pretty cheap powerful USB-UART IC. I have some plans for a set of boards for the CP2110 by itself as well.
@Pete yeah, it will need standoffs as is. A press fit would be nice, but it's pretty dense and it would be hard to route 7 signals to the other side of the board without going to 4 layers (which would bring the price up).
Thanks! I'm planning to keep updating this page often!
Why even look at 2mm headers? Are they cheaper than 2.54mm, or is there some other reason? I'm not trying to be funny; just trying to figure out what the point is in breaking with what the majority of breadboards and IDC cables support..
Physical size - breadboard-friendly single row 0.1" headers tend to make PCBs pretty big. I'm more into the module-ish idea of a main board that's real small and has a good amount of IO connections, so dual row at a smaller pitch seems to make sense.
I'm imagining a connector on the bottom side so this could be plugged down onto a base board as a CPU+power module, sort of Intel Edison style, except in the 10ドル-15 range so it might actually make some sense to plug it into a 'product' and leave it there.
It's a little annoying for breadboard use, but it wouldn't cost much to make an add-on board that adapted to 0.1" headers for prototyping.
Fair enough.
With a single 2x7, you'll still need standoffs, I suppose. You may consider breaking it into two 1x7s at opposite ends of the board and allowing press-fit to bind it to your base board..
Good luck! Looks like an interesting platform. Please keep the project updated and let us know your opinion on the outcome.
to follow this project and never miss any updates
Just wondering - why not use a microcontroller with inbuilt USB bootloader/use the factory bootloader? Many arm chips have this nowadays, either with a ROM bootloader or they come pre-flashed from the factory with a bootloader. An example would be the Freescale/NXP MKL27Z (although there is probably an equivalent NXP part): http://www.digikey.com/product-detail/en/freescale-semiconductor-nxp/MKL27Z32VFM4/MKL27Z32VFM4-ND/5361438 . Bootloader is in ROM so you can't lock yourself out (unless you set the appropriate fuse bits).
2ドル.32 in quantity 1
I guess if you made another version of the board without the usb uart section then it would be worth it, to keep 'deployed product' costs down.