People have asked if and when it would be possible to buy AAduinos. The answer to both questions is “sort of soonish” as I am about to start a crowd sourcing campaign with the good people over at Crowd Supply. Here’s their pre launch page. There are a number of cool projects running over there, Lime SDR is a personal favourite of mine.
Update Aug 28th: The BOM for all variants is now on Github. Please see the notes at the end if you want to build a Commadorable 64 yourself.
The ILI9341 based QVGA displays found on eBay for €4 are well suited for making small screenlets telling the current temperature, weather forecasts, traffic situation to work and spreading them over the house. As PCB design is both fun, cheap and rewarding I did a custom PCB for these tiny displays. Actually, I made three, one for each of the 2.2″, 2.4″ and 2.8″ screens. The 2.8″ version has not been produced but the smaller variant have and work well. From 2.4″ and onwards there is (untested) touch support on the screen modules.
The “Hello World” application for this project also named the PCBs. I call them Commadorable 64. Here is why:
The cursor blinks but I resisted the urge to create an animated GIF. “Commadorable 64” is a play with “Commodore 64” and “adorable”. It has been scientifically proven that those for whom the Commodore 64 played a significant part of their childhood will look at the 2.2″ version of the C64 start screen and react the same way as cat people looking at kittens. Heads will be tilted slightly sideways, smiles appear and sounds like “naaaaaaaw” will be heard. I have one of these at work and depending on childhood experiences people will either go “what?” or “naaaaaaw”.
The PCB is soldered directly to the pins of the ILI9341 module. Some of these screens will probably end up in other applications in the future. The other day I read about openframe.io and adding support for these would be fun.
The PCBs can be ordered from DirtyPCBs.com, 2.2″ with a bonus AAduino and 2.4″ version with touch. The BOM consists of the usual components for my ESP8266 designs. We have 0603 resistors and capacitors, a 3x6x2.5mm momentary push button [eBay] for displaying the IP address, a SOT23-3 P-mosfet to control the backlight, an LM1117 voltage regulator and a SOD-123FL schottky diode for reverse power protection and optional mini USB connectors. The PCB can be powered in three different ways depending on personal preference (well, four including the esprog interface). There are footprints for normal [eBay] and vertical [eBay] mini USB connectors, depending on if the module is to stand on a table or hang from a wall (Eagle parts available on Github). In addition there is a 0.1″ header for power. All power paths are protected by the diode.
Further update Aug 28th. I see some 20+ orders on DirtyPCBs for both Commadorable 64 variants which is great fun and I would really love to hear what you will build. I have some recommendations you might find useful. I have received a few broken ESP-12e/f modules on eBay over time and one broken ILI9341 module. Because of that I always try the modules before soldering them using my Esparducam board with the ESP Pinlet add on board. When a module passes testing I flash it with the ESP Open RTOS OTA basic demo meaning I can OTA any device directly after soldering. Also, you will note there is no FTDI connector on these boards, the reason is described here. As UART output is still useful, I have one “development” variant with leads from an FTDI connector soldered to the GND/RXI/TXO esprog pads. Oh, and I also have one Commadorable 64 board with a female header for testing the ILI9341 modules before soldering them. If you have any questions about building the boards, sound off in the comments below.
Code and schematics on Github, as always.
The ESP8266 has taken the maker community by storm and the hype is well deserved. Before the ESP we had the HopeRF ISM radio RFM12 and its successor RFM69. So is the ESP8266 an RFM69 killer? I would say no. Hell no even 🙂 The RFM69 is still very well suited for certain applications and the ESP8266 will not run for 2+ years on a set of AA batteries. The two can however play nicely together as a low cost ISM/wifi bridge. I did a custom PCB for this in the shape of a somewhat large USB stick, dubbed “Espism”.
Currently it works as an ISM sniffer posting the received packets on the MQTT topic espism-<macaddr>. Packets are posted in hex followed by the RSSI value:
espism-5ccf7f147cd Hello from 172.16.3.120
A set of four LEDs indicate received packets. Well three LEDs as I made a mistake on the ground plane. The MQTT server IP and RFM69 network information is hard coded into the binary.
I ported Andreas Heßling’s STM32 RFM driver to the lovely ESP Open RTOS, my swiss army knife for ESP8266 development. The type-A right angle 90 degreee USB connector and 3x6x2.5mm push button can be found for little money on eBay. The push button currently serves no purpose but the plan is to perform a “master reset” of the device using this button. The rest of the BOM consists of 0603 resistors and capacitors, an LM1117 3.3V regulator and a SOT23 P-mosfet for driving the 0603 LEDs. Oh, and the ESP12F talking to an RFM69CW. The BOM should add up to about the price of lunch.
The FTDI connector can be found on just about any ESP8266 design. If you are building a gadget to be deployed somewhere and not a full blown development board, the FTDI connector is somewhat overkill. And it is quite large. A few pins could be shaved off but we still have a through hole connector invading the other side of the PCB.
I ended up designing my own connector and it has been used sucessfully in all of my recent projects. The connector consists of five test points providing power, GND, TXO, RXI and GPIO0 for boot control. It takes very little single sided PCB space and is inspired by the TagConnect I use at work. Note that the power provided through the connector is unregulated.
I also designed a pogo pin connector to mate the test points and a small board with a DC barrel connector and the FTDI connector. This board has two switches for power and boot mode selection.
If you look carefully on the pogo pin adapter you see that the power pin is somewhat retracted. As the adapter will be hand held, the four other pins can be aligned to the device and with a gentle push power will be applied.
I have been using Nathan Chantrell’s Tiny328 for quite some time as my swiss army knife ISM radio node. Now I wanted a more slim ISM node as my setup with a Tiny328 on a breadboard is not very “deployable”. I could of course 3D print a case for the Tiny328 but I have limited access to 3D printers and do not feel I have the time to explore that exciting part of the maker world just yet. This leaves me with finding off the shelf project boxes with a compartment for 2x AA batteries and the “radioduino” (and in an acceptable form factor). That search came up disappointingly, and surprisingly, short. I did have a set of standard eBay AA battery holders and looking at the 3x variant it occured to me. I needed to shrink the radio node, and the AAduino was born.
The AAduino is an wireless Arduino clone the size of an AA battery with Keystone battery terminals rotated 180° to act as positive and negative terminals. It is powered by an ATMega328p and is fitted with an RFM69C companion. There is room for two DS18B20 temperature sensors and an indicator LED.
It runs at 8Mhz to allow for greater life span since the CPU can run at a lower voltage. I have fused the 328 to brown out at 1.7V which is a bit out of spec at 8Mhz and slightly below what the RFM69C needs. Running at 4Mhz would be more suitable but I will see how well the node performs when the batteries are draining out.
Since the RFM69C is somewhat wider than an AA battery I used a file to make it slightly narrower. There is some room for that kind of modification without damaging the module. Update, the RFM69C will fit without modification. Next I clipped the legs of the DS18B20 until about 5mm remained and soldered it to the 3x pin header on the AAduino. I then drilled a hole in the battery box where the sensor can protrude and a small hole for the LED to shine through. The wire out of the battery box was cut, shorted and stuffed away inside the box.
I use battery terminals from Keystone available from RS Components, positive and negative. There seems to be a cheap eBay alternative but I have not tested those. The + and – markings on the PCB indicates (this is important, read carefully) the positive and negative poles of the battery we are pretending the AAduino is. The Keystone spring contact should be soldered to the + marking and the button contact to the – marking. There is no protection diode here so be careful. Also note! If you want to power the AAduino from a bench power supply, connect the power supply’s black negative lead to the + marking and the red positive lead to the – marking.
The 3xAA boxes are also from eBay and there seem to be two different types. One that is really good and one that is really crappy. I will let you in on the secret of buying the correct one. The good ones have a nice build quality and plastics and look like this. Note the rectangular piece of plastic below the battery compartment extending from side to side.
Looking at the crappy ones, well you can tell can’t you? In the top left corner it seems someone used a soldering iron on the poor thing. The lid does not snap in place very well and the plastics is really cheap.
Code, schematics and BOM on Github, as always.
I have had some questions about the possibility to purchase Esparducam boards and also about the bill of material. While I am looking into selling spare boards, here are some instructions about building the boards. Here is the link to order the PCBs [dirtypcbs.com].
If you have never tried building surface mounted boards yourself I highly recommend you try it! I started here [nathan.chantrell.net] and googled my way from there.
Here is the BOM with some eBay links:
C1 1uF capacitor 0603
C2 0.1uF capacitor 0603
C3 1uF capacitor 0603
C4 10uF capacitor 0603
C6 0.1uF capacitor 0603
J1 6 pin 2.54mm male header (angle) [eBay]
JP1 8 pin 2.54mm female header (for the Arducam Mini) [eBay]
JP9 Power jack 5.5×2.1mm [eBay]
R1 4k7 0603
R2 4k7 0603
R3 4k7 0603
R4 4k7 0603
S1,S2 Momentary switch [eBay]
U1 NCP1117 (or LM1117) 3.3V regulator [eBay]
The following parts are optional depending on what you want to do with your board:
Reverse current protection
D1 SOD-123FL, schottky diode for reverse current protection [eBay],
If you feel brave you can bypass the diode by placing a blob of solder across SJ2 on the back of the board.
Adding motion detection
If you want to attach a PIR [eBay] you need:
J2 JST ZH connector, 3 pin [eBay]
R6 220k 0603
R7 100k 0603
R6 and R7 was going to be a voltage divider that I messed up leaving R7 optional. Please note that the PIR does not work at 3.3V. To bypass this without adding a 5V regulator I simply feed the PIR with the raw board voltage which in my case is 5V.
Controlling power to the Arducam Mini
If you want to be able to control the power to the Arducam Mini board you need Q2 and R5. If you feel ok to have power constantly enabled simple place a blob of solder across SJ1 at the back of the board.
Q2 P mosfet, SOT-23 [eBay]
R5 4k7 0605
The external SPI flash is also optional. Please note that the footprint is somewhat too narrow, some flashes might not fit.
U2 SPI flash SOIC-8
C5 0.1uF 0603
Adding header pins
These optional headers are for attaching add-on boards or pins for taking measurements
JP3, JP6 8 pin 2.54mm male header
JP4,JP5 8 pin 2.54mm female header
That’s it, good luck!