The Raspberry Pi 3 Model A+, the unknown entity
Recently, I had a very interesting "aha" moment while developing the new control for drop photography. Maybe it was only new for me, but in case it is not, I still want to report about it briefly.
In the past years I have done some more or less big projects with a Raspberry Pi. The decision which model to use was always very easy. The Raspberry Pi 4 is very powerful, but completely oversized for my needs. And since I don't want to use any old hardware, apart from the Raspberry Pi Zero W, only the Raspberry Pi 3 Model B+ remains. At least that's what I thought.
While searching for info about the Raspberry Pi Touch Display, I eventually landed on the Raspberry website. While scrolling through the products, I noticed the Raspberry Pi 3 Model A+. I could not believe my eyes. This is exactly what I need. I almost always disable the USB/LAN chip and also the HDMI output, because I only need the WLAN and the GPIO ports. Why I don't use the Raspberry Pi Zero W or even an Arduino, I will explain in a moment. Before that, a small overview to clarify the differences between the models:
|Arduino Uno||Zero W||3 Mod. A+||3 Mod. B+|
|Length||68,6 mm||65,0 mm||65,0 mm||85,6 mm|
|Width||53,3 mm||30,0 mm||56,0 mm||56,0 mm|
|Height||12,5 mm||5,0 mm||12,0 mm||20,0 mm|
|CPU||ATmega328P (8 Bit)||ARMv6 (32 Bit)||Armv8 (64 Bit)||Armv8 (64 Bit)|
|Clock||16 MHz||1000 MHz||1400 MHz||1400 MHz|
|RAM||32 KB Flash + 2 KB SRAM||512 MB||512 MB||1024 MB|
|WLAN||-||2,4 GHz b/g/n||2,4 u. 5 GHz ac||2,4 u. 5 GHz ac|
|Power||0.29 W||0,5–0,7 W||max. 4,24 W||max. 7 W|
|USB 2.0||1||1 OTG||1||4|
|Interfaces||GPIO (14 Digital, 6 Analog), SPI, ICSP, I²C||GPIO (26 Digital), CSI, I²C||GPIO (26 Digital), CSI, DSI, I²C||GPIO (26 Digital), CSI, DSI, I²C|
|Price||22 Euro||12 Euro||25 Euro||38 Euro|
The suitable hardware depends, of course, on the respective requirements. For the drop controller, for example, the following criteria were important:
- Programmable in a high-level language (Python, Java)
- DSI interface
- Low power consumption
- WLAN, ideally 5 GHz
- Low space requirement
In the table above, the values that most closely meet the criteria are marked in color. And as you can see, the Raspberry Pi 3 Model A+ meets all of them. And in my other projects, the criteria were quite similar. I just can't believe that so many hobbyists need the Ethernet and all 4 USB ports. But as I said, of course the requirements depend on the project. Still, it's a mystery to me why the Pi 3 Model A+ is so unknown. A good example is the image search on Google. The search term Raspberry returns almost exclusively the B+ models. Even otherwise, I haven't come across any project that uses the Raspberry Pi 3 Model A+. And that, although it has been available for purchase since the end of 2018.
In any case, I will only use the Pi 3 Model A+ in the future, as long as my requirements do not change. It is a cheap and space-saving alternative to the Raspberry Pi 3 Model B+, if you can live without Ethernet and get by with one USB 2.0 port.