Comments on: Parts: LTC2631A I2C digital to analog converter

By: elektrophreak

elektrophreak — Mon, 14 Jun 2010 11:32:39 +0000

@Ian Lesnet

Thanks for this info !

By: Ian Lesnet

Ian Lesnet — Wed, 11 Feb 2009 08:07:14 +0000

@stu I used the tlc5940 in my home lighting system, si-light. The TLC5940 has an SPI interface to the PWM registers, but the data out is primarily useful for cascading multiple chips. The tricky part about the TLC5940 is that you must provide your own clock and reset. You provide 4096 clock ticks, and then trip the reset pin. Inside, the 5940 has counters that turn off the LED when the clock ticks equal the duty cycle you program through the SPI interface; all come back on when the reset pin is triggered. As I recall, I connected the oscillator output of a PIC16F628a to the TLC5940 clock input, and used the PIC's counter to count to 4096 and then toggle the reset pin on an interrupt. Now, can this be done with the Bus Pirate? Sure, but it will need a new module that creates the clock signal on one AUX pin and the reset on the other. This isn't difficult, but it's not a feature the Bus Pirate currently has.

By: Stu

Stu — Tue, 10 Feb 2009 21:53:41 +0000

Oh BTW.
This is what I’m doing with the pair of MAX6956 chips and a 16F88 –

I even wrote a little VB prog that allows you to generate the patterns with a GUI, it outputs PicBasic DATA blocks for you to paste into the PBP program. You then simply compile, then flash the F88. Job done.

By: Stu

Stu — Tue, 10 Feb 2009 21:45:15 +0000

I’ve got a chip for you guys to try out with the BusPirate, I bet you’d have troubles like I did.
Its a Texas Instruments TLC5940 LED driver chip.
I held great promise thinking this chip would be easy to interface. Not being a professionally taught electronics person, I found it almost impossible to use. Not only is the Data Sheet nigh on useless, I didn’t recognise the serial comms format it uses, even building a proto board for it was difficult.
I tried interfacing it with a PIC 16F88 chip using PICBasic Pro. Couldn’t even get it to light any of the LEDs.
I since switched to a pair of Maxim MAX6956 chips on one i2c bus – INFINITELY easier to use because it uses i2c, a great protocol, library routines already built into PicBasic Pro.

By: โปรแกรมแปลงไฟล์

โปรแกรมแปลงไฟล์ — Tue, 10 Feb 2009 13:14:07 +0000

Cool software
thank

By: r4d10n

r4d10n — Tue, 10 Feb 2009 12:02:19 +0000

great post !! it will great if u can do a parts post on some of the high speed ADCs like LTC2209 which can be useful a lot of people who want to do all sorts of sampling operations…

By: dan

dan — Tue, 10 Feb 2009 06:58:52 +0000

The parts articles are great, I plan on building a bus pirate as soon as I get some free time. My suggestion for a future article is the MCP6S26 programmable gain amplifier from Microchip. PGA chips seem like a good way of taking some of the headaches out of amplifier design and the multiple inputs allow one to switch various filters in and out of the circuit. Another part you may consider covering is one of the digital potentiometer chips.

By: Ion

Ion — Tue, 10 Feb 2009 01:47:16 +0000

YAY another parts post, I love these, and this ones a doozy