interface with 3 rows of 4 7-segment display using i2c?

[espruino-discuss2]

Posted at 2014-11-07 by d0773d

I would like to control 3 rows of 4-digit(with the decimal) 7-segment displays using i2c.
The display that I would like to use can be found here: https://www.sparkfun.com/products/11408

Is there a IC that exists to drive 3 rows of 7-segment display mentioned above using i2c?

[gfwilliams]

Posted at 2014-11-07 by @gfwilliams

Do you have to use I2C? You can use this chip:

http://www.espruino.com/MAX7219

On that page some modules are shown that include it already, but you can always wire up your own. It'll do brightness too.

It uses 2 wire clock+data, so still 2 wires, but no pullups. You can then chain the modules end to end in order to have any number of LEDs.

Also, because it's using SPI you can use 'soft SPI' which means you can use any two pins on Espruino for it.

[espruino-discuss2]

Posted at 2014-11-07 by d0773d

i2c isnt neceassary, I can use spi. Thanks!

[espruino-discuss2]

Posted at 2014-11-08 by d0773d

@gordon I will most likely go the max7219 route. Just out of curiousity, how hard(code wise) would it be to implement:http://www.maximintegrated.com/en/products/power/display-power-control/MAX6955.html ?

[espruino-discuss2]

Posted at 2014-11-08 by DrAzzy

Well, that chip has a very rich feature set to write wrappers for, which makes a bigger job, if want expose the features, , but writing a for it probably wouldn't be that hard. What is hard, is justifying the price - digikey wants almost twenty five bucks a pop for them...

[espruino-discuss2]

Posted at 2014-11-08 by d0773d

For 25 dollars I could probably purchase the max7219 chip with a 4 digit 7-segment display. I will stick with a max7219 chip and use multiples of them if need be.

[espruino-discuss2]

Posted at 2014-11-08 by d0773d

@drazzy @gordon I purchased one of these:https://www.adafruit.com/products/881 without doing research on the ht16k33 chip because I thought it would be relatively easy for me to port the arduino and python code to javascript, however I was wrong. After some more research I stumbled across:https://github.com/mdobson/tessel-ht16k33?files=1
I haven't received the 7-segment from Adafruit yet so I wasn't able to attempt to port the code to the Espruino yet. Is the ht16k33 relatively easy to port over to the Espruino?

[espruino-discuss2]

Posted at 2014-11-09 by DrAzzy

Datasheet doesn't make it look too bad. Only a handful of commands, and it doesn't look like it wants you to do any particularly weird stuff. Looks like the module'd be pretty easy to write.

Writing off the top of my head looking at the datasheet, I'd start like

exports.connect = function(i2c,address,) {
    return new HT16K33(i2c,range);
}

function HT16K33(i2c,address) {
  this.i2c = i2c;
  this.a=(address?address:0x70);
}

HT16K33.prototype.send = function(data){
	this.i2c.writeTo(this.a,0x00,data);
}

HT16K33.prototype.setBrightness = function(bright){
	this.i2c.writeTo(this.a,0xE0+E.clip(0,bright,16));
}

HT16K33.prototype.setDisplay = function(on,blink) { //blink - 0 = no blink, 1=2 blink per second, 2=1 blink per second, 3=1 blink per 2 second
	this.i2c.writeTo(this.a,0x80+(on?1:0)+(E.clip(0,blink,3)<<1));
}

[espruino-discuss2]

Posted at 2017-03-01 by LeFree

Hi Gordon,
I've been trying to control my 4 digit seven segment with ht16k33 back pack using Rpi and C codes i've found online (yeah, i'm a beginner and i don't really know how this works).
Could you write a quick sample simple code that displays numbers on the 4 digit seven seg?
Thanks

[espruino-discuss2]

Posted at 2017-03-01 by @MaBecker

Hi @Lefree,

check thingsSDK/ht16k33

[espruino-discuss2]

Posted at 2017-03-01 by LeFree

yeah thanks MaBe, but i haven't found a code in C for Rpi that works from all the resources i found through your link

[espruino-discuss2]

Posted at 2017-03-01 by @MaBecker

there are two on github

[espruino-discuss2]

Posted at 2017-03-01 by LeFree

I'm using a 4 digit seven segment; the code isn't compiling at all. no such file in directory is displayed as error. Isn't there any simple C code for Rpi to drive a 4 digit seven segment with the ht16k33 back pack......

[gfwilliams]

Posted at 2017-03-01 by @gfwilliams

I can't be much help - this is really a forum for the Espruino JavaScript interpreter.

You could however compile that and run it - with the code above - on the Pi :) While I don't think hardware I2C is properly implemented, you could use software I2C on any GPIO pins.