Saturday, December 8, 2018
ESP8266 library for EFM8 microcontrollers
Thursday, July 12, 2018
AVR EEPROM Library | ATmega328P
- Flash memory - for the program code
- SRAM memory - also referred as data memory (volatile memory)
- EEPROM memory
Normally, to make use of the EEPROM memory, you would have to read the datasheet and implement some read/write functions using some registers. But fear not - the AVR-GCC compiler comes with prebuilt routines making things much easier.
Friday, July 6, 2018
How to tin your PCB using plumber's paste | Homemade PCB
The last step in making your own printed circuit board (PCB) is tinning. Tinning is important because copper oxidize very fast, leading to an ugly look, hard to solder pads and over longer time, breaks in traces.
When you order PCB's from a manufacturer, the pads look all nice a shiny. I was looking for a way to achieve this at home and I found one. It doesn't involve strong chemicals, it's cheap and it only takes a few minutes.
Example of homemade PCB tinning |
PCB after tinning |
PCB before tinning |
Thursday, May 24, 2018
Analog to Digital Converter (ADC) library for AVR microcontrollers
This library provides a quick and easy way to set up an ADC on AVR
microcontrollers and retrieve the values in 8-bit or 10-bit format in an
interrupt driven fashion.
Nowadays even the cheapest microcontroller has a build-in ADC (Analog to Digital Converter). An ADC converts analog signals into digital signals and can be used in a wide range of applications like recording a signal from a microphone into a digital format, reading light sensors like an LDR (light dependent resistor), measuring current consumption, reading temperature or humidity sensors, etc. All these requires voltage measurements that an ADC can do.
Wednesday, May 23, 2018
Watchdog library | AVR microcontrollers | ATmega328P
Even if you are a dog or a cat person, you should still be using the watchdog.
For those who don't know, a watchdog is a timer inside the microcontroller generated by an RC oscillator - with 128kHz frequency on an AVR device. When it times out, the microcontroller is reset. To prevent it from resetting the MCU, the watchdog timer must be reset by the code inside the while loop. The idea is that if you have a loop and gets stuck, the watchdog timer will not be reset and so the microcontroller will be reset after the timer reaches the timeout period. Say you read a sensor and in a loop the code waits for the sensor response but the sensor is malfunctioning. If not for the watchdog, the MCU will get stuck and your drone will crash.
On ATmega328 the available timeouts are 16ms, 32ms, 64ms, 0.125s, 0.25s, 0.5s, 1s, 2s, 4s, 8s. Choosing the right timeout depends on the specific application. The while loop must be able to finish executing the code and reset the watchdog timer before the timer runs out. For critical applications where if the CPU being stuck for more than 1 second is unacceptable, you can choose timeouts of a few milliseconds. Those cases can be a drone where reaction time needs to be fast, or a 3D printer reaches the end and the motor needs to be stopped in time. But in most cases the timeout can even be 8s, like when taking room temperature readings.