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Jaluino Bee v2.0

(but where is v1.0 ?...)

I've been working for several months by now on a new Jaluino board, Jaluino Bee. I've designed a first PCB (v1.0), tested it with more or less success and now have ordered (and received) a second batch of PCBs (v2.0). From all i could test it seems to work "out of the box", so now is the time to expose this...

Upper three board: Bee v1.0 with more or less "green wire" fixes. From left to right: Jaluino Bee[z] powered by PIC18F25K22, Jaluino Bee powered by PIC18F27J53 (lots of fixes...) and Jaluino Bee[p] powered by PIC18F2550 (because I had some in my box...). On the bottom, Jaluino Bee v2.0 powered by PIC18F27J53 (no more "green wire" fixes), sweet...

By the time I started to design Bee, I had the following constraint: provide a board as cheap as possible, with several options depending on user's needs. This is one reason why I switched to SMD components and one main different characteristic from Jaluino Medium, for instance.

So Jaluino Bee is a small, 5cm x 5cm, board, using mostly SMD components. I had two microcontrollers in mind when I designed it: PIC18F27J53 and PIC18F25K22. Both are recent Microchip microcontrollers. 18F27J53 is USB capable, amongst many other very interesting features (RTCC for instance), while 18F25K22 isn't USB capable but can run very fast (16MIPS). Both are supported by Bee though, I must admit, I've been playing much more with PIC18F27J53.

 

Jaluino Bee v2.0, top side



Jaluino Bee v2.0, bottom side


So here some more bullet point specifications. Some are common, others depend on select MCU (18F2550 is here just for the comparison with more modern PICs -- and also in case you have one in your box --):

 PIC18F27J53PIC18F25K22PIC18F2550
RAM 3.8K  
Program memory128K   
Max. speed 48MHz (12 MIPS) 64MHz (16 MIPS) 48MHz (12MIPS)
USB YesNo Yes 
RTCCYes No No 
Internal oscYes, and USB low speed Yes Yes (but no USB at all) 
Power supply 3V3up to 5Vup to 5V  
Serial 2
I²C
SPI
Remappable pins YesNo No 
CCP
ADC channels13 (12 bits)19 (10 bits)  13 (10 bits)
Price (Microchip, volume pricing)$2.66$1.62$3.44

 

PIC18F27J53 is a nice MCU, worth the money.

In addition to this list, we can add the following common features:

  • Micro SD-Card slot (not compatible with PIC18F2550)
  • 3V3 power supply (no more 3V3/5V conversion, most nice little chips/module are 3V3)
  • Reset-via-RTS feature
  • On-board LED
  • Powered by USB and external batteries (can skip voltage regulator to use 2x1.5V AAA batteries)
  • Optional pullups placeholders on many pins if your application needs it (well, you can add them on all SPI lines for instance if case you've troubles with SD-Cards...)
  • Resettable fuse (250mA, on the safe side)
  • Xbee socket allowing to plug, well, Xbee modules, but RFBee, Bluetooth Bee modules. Xbee socket also comes with optional
  • Amazingly sweet, nice, great looking board :)
Micro SD-Card slot. Small chip beside is a 23K256 optional extra memory

Jaluino Bee can also have a optional, extra memory chip (not compatible with PIC18F2550). Depending on the needs, this chip can be (same pinout):

  • 23K256 SRAM: to give an extra RAM amount for greedy applications
  • SST25VF010A TransFlash: if you don't need SD-Card but still want some flash memory
  • 25LC080SN EEPROM: because PIC18F27J53 doesn't have EEPROM... Just in case.


I've also designed a small shield, mini-Crumboard shield. It comes with a prototyping area (PTH components) as well as several SMD pads (SOIC, SSOP, SOT, etc...). Hopefully this shield can be used either as a prototyping one, or as a final application shield.

Mini-Crumboard shield, with PTH area and SMD pads on both sides

A small breadboard can be used to provide an easy-to-use prototyping area

Plugged over Bee

Not shown here but Xbee module can still be used when shield is on top of Bee

 

So what now ? Well, when I sourced SMD components, this was a real nightmare... And though you get cheap components, you often get hundreds of them. So I may be able to provide kits. Without extra memory chip, and Xbee module of course, I'd expect such a kit to cost ~$10...

To be continued !

 

Cheers 
Seb