Computing stuff tied to the physical world

The JeeNode USB v3 has arrived

In Hardware on Apr 9, 2010 at 00:01

Well, I finally got around to finishing the details (ehm… at least some) of the new JeeNode USB v3.

I’ve added it to the Shop, replacing the older JeeNode USB v2. Starting now, all JU’s sent out will be v3’s.

As you may recall, the main reason for bringing out a new version was because the v2 model had the 3.3V on-board regulator mounting messed up, requiring manual fixes to be made for each unit.

The new v3 board has the regulator mounted correctly. Here is a list of all the differences, since a new run gave me the opportunity to do a bit more:

  • The 3.3V regulator is now also used to supply power to the ATmega and RFM12B. This improves ADC accuracy, since running the ATmega off the FTDI regulator and bringing out 3.3V from another regulator isn’t really a good idea.

  • The RFM12B has been moved to the side a bit, to make room for a pad with hole to solder the antenna wire to. Less risk of it breaking off during use.

  • The board length has been increased (80.7 mm vs 79.8 mm) so the RFM12B no longer sticks out.

  • The USB jack has been moved out a bit, so now it sticks out. This will be more convenient when mounting the board flush against the outer wall of some enclosure.

  • There is now an on-board MAX1555 Lithium Polymer battery charge chip on board, as well as an orange LED, which lights up while the circuit is charging.

  • As a result, the PWR pins brought out on the port headers, etc, will now be at 4.2V instead of 5V, while plugged into USB. When on battery power, it will be whatever the battery supplies. You can still connect other types of batteries to the PWR pin to power the unit, as long as their voltage does not exceed 5V!

  • The on-board FTDI chip used for USB comms will be unpowered while running off batteries, to lower power consumption (it draws a few mA).

  • There is an on-board voltage divider connected to PWR, so that the ATmega can monitor the current battery voltage level. This is a high-impedance divider.

Oh, and since I got bored with just fixing things, I decided to throw a fresh bug into the mix ;)

The current boards have some incorrect silkscreen labels:

Juv 3 Silkscreen Errors

Just ignore ’em. The P1 / P2 / P3 / P4 labels are the proper ones. FWIW: this was caused by panelizing this board in EAGLE without moving the labels out of the NAME layer. Probably a common (beginner’s?) mistake.

Anyway, I’ll get new boards made once my small initial batch runs out. Speaking of batches… I’ve now got lots of obsolete “JeeNode USB v2” pcb’s :(

Comes with the territory, I guess: bugs in the atom world lead to REAL junk!

  1. That’s alright, you can send your “junk” to me. :)

    -just another hominid

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