Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Taking full control of devices devices with power playground

When working with power devices it is always good to know what is going on. Especially this is important when experimenting with unknown parameter devices like motors, inductors or batteries. Dorkbotpdx shared a power playground that would allow to run different things and have full control and feedback of process. He used PMOS/NMOS H-Bridge configuration attached to Teensy-3.1 microcontroller board which runs FreeRTOS. There is a current sensor next to bridge which helps on experiments with PWM motor control, power line synchronization, battery charging/discharging. Four digit 7-segment LED indicator gives a simple visual feedback. This is a great tool for many interesting experiments. Continue reading

Optimizing SPI TFT displays for Teensy 3.1

SPI driven TFT LCDs are common way of getting graphical interface on Arduino based hardware. From Arduino perspective you just grab one of existing library like Adafruit’s TFT LCD library and with few lines of code you can get your graphics on screen. But the problem is that library is meant to be used on Arduino boards like UNO that are limited in resources like speed and memory. SO using same library on boards like Teensy 3.1 is loosing its potential. Paul Stoffregen took this library and adapted it for Teensy 3.1 to use its benefits in order to gain much better performance. Teensy 3.1 is ARM based 32 bit board, so there are plenty ways to improve things. First of all he took advantage of SPI speed. If Arduino can drive SPI at 8MHz, Teensy 3.1 can go up to 24MHz. Another improvement is 4 level FIFO buffer in Teensy 3.1 SPI port. So software don’t have to wait until transmit is complete before sending another byte. In other words, software can write byte to SPI while it is… Continue reading