Recent content by cmason

Note that this appears to be for the nRF8001 chips in particular a specific BLE shield. It's cool that they're officially supporting the Arduino community. However, it seems like there are already existing open source libraries for this external SPI-protocol BLE chip. This is not, however...

Hi Alistair, Yeah, I've spent a significant amount of time with the nRF51822 chips, albeit first with their dev kit and then with a custom board (which also includes EPaper display hardware). The chip is easily the best documented part I've ever worked with and quite capable. You don't need...

Random question: if I only have one SD card slot on the SPI bus, do I need to use a pin for Chip Select or can I simply ground it?

I have the Adafruit e-paper display working with the teensy 3. I'm trying to make a board that has the example circuit for that epaper display. I'm trying to understand and perhaps simplify a specific part of this circuit: The complete circuit diagram is here. The epaper display is spec'd...

I have this working on teensy 3 here. Main program here. As Paul said, it's just a matter of editing code. :) -c

I re-read my comments above, and while I think they are all true, they're not very concretely helpful. I'd like to help, though. To that end, I've written a simple test program. The main guts of it are: string hello = "hello "; uint32_t size = 10; vector<string> vec; vec.reserve(size)...

I'm making pretty extensive use of stl and C++ in a project. I mostly create containers at startup at startup, use reserve() to preallocate, and try to avoid extending them beyond that allocated size. I've wrapped the STL containers so that in the future I could replace them with fixed sized...

I'm looking for a good fixed point math library for some graphics stuff. Needs to have trig. Nice to have a C++ library with operator overloading. Nice to have something that's optimized for ARM. Has anyone used a fixed point library? Which one? Thanks, -c

I spent a bunch of time messing with the SPI unit before finally getting it to work. I haven't tried to use it as a slave. Three things that helped me: Make sure you enable the clock to the SPI unit: // Enable Clock to SPI. from page 241 of Kinetis K20 Reference Manual. SIM_SCGC6 |=...

The teensy always runs the flashed program when it is started regardless of whether it is connected to USB. Is it possible that you're doing something which is requiring USB? You didn't say which teensy you're using, but I had some programs for the teensy 3 that did something like...

Scott and I reflowed the chip and then spent some time with his scope. Without enabling the t3's internal pullups, with just 10k external resistors we were seeing some significant ramping on the sda line. I'm concerned that, due to some of the issues mentioned elsewhere, the T3's internal...

I'm trying to talk to this MAX17048 battery fuel gauge. I designed a board and soldered it using a hot plate. I fear I may have either not completely soldered it or may have fried the chip during soldering because I can't seem to talk to it. However, this is the first time I've used I2C and...

Has anyone succeeded in using the emulated SPI code to run the AVR-ISP program in the arduino examples directory on a teensy 3? I'm trying to program a ATMEGA328P-PU and I'm getting the following: > /usr/local/CrossPack-AVR/bin/avrdude -c arduino -p m328p -P /dev/tty.usbmodem12341 -b 19200...

I would love to see a bit better API for sysex. It took a bit of effort to figure out the current one. In particular that the length was in usb_midi_msg_data1 and that this was an 8bit quantity and therefore we couldn't receive messages larger than 254 bytes or so (because of begin and end...

Sorry if this is a FAQ, but I'd like to control grounded AC mains devices with a teensy 3 (3.3V). Obviously I can just use a relay with a low enough coil current and a high enough rating. However, I'd rather not do this wiring myself, mostly because the devices controlled are fairly inductive...