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46  Using Arduino / General Electronics / Re: Building a function generator on: May 01, 2011, 06:25:50 am
You could make a function generator with a uC and a DAC. You store
the waveforms in wavetables (C arrays) and then periodically output
the values from the wavetable to the DAC. You can generate any arbitrary
periodic waveform. One name for this is a numerically-controlled
oscillator (NCO)

I make a board (NB1A) that integrates a '328 (Arduino bootloader)
and a DAC. I have a NCO sketch at
You could wire the same DAC to an Arduino. The schematic is in
the NB1A datasheet

(* jcl *)
47  Using Arduino / Audio / Re: New MIDI Interface on: April 23, 2011, 09:44:20 am
Hadn't heard of them until now. Thanks for the link.

(* jcl *)
48  Using Arduino / LEDs and Multiplexing / 32 Channel TLC5940 Board on: April 19, 2011, 08:08:53 pm
I have just introduced a 32 channel LED driver that is compatible with by NB1A, NB1 and
ZB1 board. The board works with the Arduino Tlc5940 library.

Features --

    * LEDs are powered by a separate adjustable
        linear regulator. Power dissipation in
        the '5940's can be minimized by adjusting
        the anode voltage just above the LED
    * Number of channels can be increased
        by using multiple cards and the
        NB1A backplane
    * Current per channel can be increased
        by paralleling cards.
    * Can be used with low-cost IDE cables.
        See Knight-Rider demo at

(* jcl *)
49  Using Arduino / Audio / New MIDI Interface on: April 19, 2011, 07:59:01 pm
I just introduced a MIDI interface board that is compatible with my NB1A, NB1 and ZB1
boards. The board features a MIDI input, output and four two-pole filters (for waveform
smoothing). I have also added a transistor to disable MIDI input on bootup.
The board works with the Arduino MIDI 3.0 library.

The schematic, BOM, assembly documentation and usage hints are in the datasheet at

(* jcl *)
50  Development / Other Hardware Development / Re: PICOBEE on: April 17, 2011, 08:12:33 pm
This board is a 3.3V board. The maximum specified frequency in the datasheet for 3.3V is around 13MHz
so I chose 12MHz.

(* jcl *)
51  Development / Other Hardware Development / 32 Channel LED Driver Board on: April 17, 2011, 08:09:39 pm
The second board in my spring-time lineup is a 32-channel LED driver.
Two 5940's daisy chained. This board works with the ZB1, NB1 and NB1A.
The outputs go to two header connectors. The pinout is compatible with
the keyed IDE cables used in a lot of PCs.

The demo at
is the Knight-Rider demo that comes with the 5940 library. I just
changed NUM_TLCS to 2. The board will be priced at $20.
I should have the schematic and datasheet later this

It is easy to get increased current out of each channel using parallel
boards on a single ribbon cable.

(* jcl *)
52  Development / Other Hardware Development / Re: PICOBEE on: April 17, 2011, 08:00:36 pm
The PICOBEE datasheet with schematic, BOM and assembly instructions is at

I will have a couple of software examples posted in the next few weeks.

(* jcl *)
53  Using Arduino / Project Guidance / Re: Capacitance to Voltage Converter on: March 28, 2011, 07:03:40 pm
I would use the timer.

Pass a 1uA (or less) current through the capacitor and measure
the time it takes to reach a specific value. Start the timer
when the capacitor starts charging and stop it
using the analog comparator.

Calculate C using   I = C * dv / dt

(* jcl *)
54  Development / Other Hardware Development / Re: PICOBEE on: March 27, 2011, 12:05:50 pm
What can you think of that needs wireless and couldn't have a RTC smiley-grin

I agree  smiley-wink

  • Timestamps for datalogging
  • Wakeup timer for datalogging/transmission

Are the two that come immediately to mind.

(* jcl *)
55  Development / Other Hardware Development / PICOBEE on: March 26, 2011, 01:55:08 pm
First new board of Spring -- PICOBEE
'328  (Arduino bootloader) + RTC (with battery backup) + XBee

Prototypes should be in around 2-3weeks.
Details at

(* jcl *)
56  Using Arduino / Networking, Protocols, and Devices / Re: Has anyone converted an Xbee chip antenna to a wire version? on: March 26, 2011, 09:27:18 am

I wouldn't risk bricking the XBee. See if you can trade with someone.

(* jcl *)
57  Using Arduino / Project Guidance / Re: Barebones arduino on: March 26, 2011, 09:03:44 am
You could take a look at the schematic and BOM for my PICO
board. Just eliminate the things you do not need.

Things I would keep --

  • filtering for ADC Vcc
  • protection diode for the reset pin
  • decoupling caps close to the appropriate pins

(* jcl *)
58  Using Arduino / Project Guidance / Re: Looking for advice on real time clock on: March 26, 2011, 08:03:34 am
I have been using the DS1337 on a number of my boards.
I like having the two interrupt lines (or one interrupt line and square wave output).

I diode-or (low Vf Schotky) the Vcc with a CR1220 coin-cell. Should last for apx 10years.

One thing to be careful of is the crystal selection. Some of the DS chips require 6pF and others 12pF.
Make sure you get the appropriate crystal.

The schematic and BOM for my PICO1TRC which uses a '328 and DS1337 is at

(* jcl *)
59  Community / Bar Sport / Re: Happy PI-day (almost) on: March 13, 2011, 03:56:58 pm
or just remember 3.141592654

As was mentioned 22/7 is useful for primary school kids.

Can also be useful for doing quick approximations in your

(* jcl *)

60  Using Arduino / General Electronics / Re: Can some one help me with a PCB layout? on: March 12, 2011, 05:03:12 pm
Your best off posting in PDF or possibly JPEG.

If I see a PDF schematic I will often view it since
it is quick to do and requires a viewer the browser
already recognizes.

If I see a schematic in Kicad/Eagle/.. etc I can't
view it.

(* jcl *)
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