Powering the Raspberry PI A+ with 4xAA batteries

This is a migrated version of my Wordpress post, written on : 8 Mars 2015

I used the Pi as a brain of an autonomous car toy project, for such project, autonomy is alway a key factor that must be considered. So i did some researches to find an efficient way to power the Pi with battery. In my project, i used 4xAA batteries as power source ('cause those ones are very popular and easy to find).

Power saving

To save the power, my suggest is to use the PI A+, this version of Pi is the less energy consuming in its family. In headless mode (without HDMI,camera, Idling in the command line), it requires around 100mA - 120mA (with or without an USB wireless attached for network communication).

The first thing you need to do is turn off the HDMI output, this can help you save about 20mA. Notes, without the HDMI, you can only access to the Pi via network using ssh (that is, you need to configure the network to work with ssh before turning the HDMI off).

tvservice -off

Programming the LPC1114FN28 using Raspberry Pi

This is a migrated version of my Wordpress post, written on : 27 February 2015

I had some Raspberries Pi A+ available on the toolbox, and i've just got idea to use one of them in my programmable car toy project. The point is that the Pi will be connected to a circuit based on the LPC1114FN28, in which, the ARM cortex M0 chip is used to collect sensor datas (IR sensor, sonar sensor, etc.) and control the motors on the car. The Pi talks to the LPC1114FN28 via a serial connection (UART or SPI), and takes care of some high level calculations based on the datas provided by the LPC chip, it then can analyse the environment's context and send commands to the slave chip to control the car. With the Pi, i can build an API to program the car's behaviour from distance via the network (using TCP protocol or HTTP protocol, via web). It's quite an interesting sujet for me.

So the first thing comes to my mind is that during the experiments, i will need to frequently update the firmware on the LPC1114FN28, so why not use the PI as a programmer for the LPC chip. The firmware is written and compiled on your PC and then is updated on the slave chip by sending it to the PI, no need to used the USB-serial adapter anymore. In this post, i'll show you how to do it, this is a part of my actual project.

ARM-Cortex M0 programming with lpc1114FN28 - an overview

This is a migrated version of my Wordpress post, written on : 27 February 2015

What is it?

The lpc1114FN28 is a low cost, low power 32 bit MCU designed in a 28dip package, it is breadboard friendly and very easy to set up for those who are new to ARM programming (like me). Some features :

  • An ARM cortex M0 processor, can run at the frequency up to 50 Hhz.
  • Built-in Nested Vectored Interrupt Controller (NVIC)
  • 32 kb on chip flash programming memory and 4kb of RAM
  • In-System Programming (ISP) and In-Application Programming (IAP)
  • UART, I2C, SPI, 10 bits ADC
  • Up to 22pins GPIO
  • And more..

It is designed mainly for micro-controller stuffs (applications), and can be easily programmed with a few more components. In fact, i'm just ancomputer scientist guy who is new to the MCU (ARM) world and that simplicity is a good point for me. I've bought some of them from Ebayand started to learn how to program it.

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