I2C to LED 7 Segment driver - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: October 04, 2022, 06:20:13 pm
content: I'm looking for low cost solution to drive 8 digit 7 segment (LED) display through 12CI know they are often drive through 595 IC but I believe it will need more pins.

author: rstofer
author_rank: Super Contributor
timestamp: October 04, 2022, 06:26:06 pm
content: Maxim makes an entire line of 7 segment drivers that work on I2C like:https://datasheets.maximintegrated.com/en/ds/MAX6955.pdfDefinitely not 'low cost' at $22 but I only needed one. Mouser has stock.

author: mikerj
author_rank: Super Contributor
timestamp: October 04, 2022, 06:33:59 pm
content: Check out the Holtek HT16K33. This IC is used on the cheap four digit, 7 segment modules you get pick up from eBay etc.

author: kripton2035
author_rank: Super Contributor
timestamp: October 04, 2022, 06:36:24 pm
content: TM1637 1638 are used in cheap display modules. they can drive some buttons too.https://www.aliexpress.com/item/32805933184.htmlthe chip alone (by 10 pieces) :https://www.aliexpress.com/item/1005003822582905.html

author: MikeK
author_rank: Super Contributor
timestamp: October 04, 2022, 06:37:35 pm
content: There are plenty of 8-digit 7-segment display modules on eBay for a few dollars. They use the MAX7219 chip. And when I purchased some in 2020 the modules were cheaper than just buying the chip.

author: mariush
author_rank: Super Contributor
timestamp: October 04, 2022, 06:49:56 pm
content: You may be able to use generic led drivers if for example you use separate common cathode digits or groups of digits with common cathodes per digit.For example IS31FL3728 could do it, I think :https://www.digikey.com/en/products/detail/lumissil-microsystems/IS31FL3728-QFLS2-TR/5319755(datasheet :https://www.lumissil.com/assets/pdf/core/IS31FL3728_DS.pdf)IS31FL3728 is a general purpose 8×8 LED matrix driver which features an audio frequency equalizer (EQ) mode or a general LED dot matrix display mode.The general LED matrix display defaults to an 8×8 configuration, however, it can be configured for a 5×11, 6×10, 7×9 dot matrix display. 5~8 current source outputs for row control 8~11 outputs for column scan control Programmable 8×8, 7×9, 6×10, 5×11 matrixHere's a tutorial where he does 4 7 segment digits and some rgb bar graph :https://rheingoldheavy.com/i2c-display-v2-tutorial-01-is31fl3728-display-driver/Or you could have a simpler 28 channel driver and use 2-3 mosfets to switch power between groups of 4 digits (7 segments x 4 = 28 channels)ex :https://www.digikey.com/en/products/detail/lumissil-microsystems/IS31FL3235A-QFLS2-TR/7219609(datasheethttps://www.lumissil.com/assets/pdf/core/IS31FL3235A_DS.pdf)

author: ledtester
author_rank: Super Contributor
timestamp: October 04, 2022, 09:02:33 pm
content: Quote from: sairfan1 on October 04, 2022, 06:20:13 pmYou can do 8 digits with two 595 chips... see, for instance:https://www.aliexpress.us/item/2255801121812599.htmland:https://www.aliexpress.us/item/2251832655784610.htmlBack side of the boards:

author: james_s
author_rank: Super Contributor
timestamp: October 04, 2022, 09:44:18 pm
content: I've never been able to figure out what's up with the cheap MAX7219 ICs that are available all over. They cost a small fraction of what Maxim charges so I assume they must be fake, but on the other hand I've used them and I've read articles where people tested them and the performance seems to be identical in every visible way to the genuine parts. At any rate I would not hesitate to use the cheap ones, I've never had any issue at all.

author: edavid
author_rank: Super Contributor
timestamp: October 04, 2022, 11:41:34 pm
content: Quote from: james_s on October 04, 2022, 09:44:18 pmHere's a thread with die photos:https://forum.arduino.cc/t/maxim-7219-real-and-fake-compared/226823The clones are only 1/4 the die area, and of course Maxim is known for high prices.

author: james_s
author_rank: Super Contributor
timestamp: October 05, 2022, 12:41:14 am
content: That's interesting, I'm surprised they seem to work absolutely perfectly, and the smaller die suggests they're a more modern part. It's too bad they sell them as fakes instead of putting their own part number on them, maybe some other prefix followed by "7219" to denote their own version of the part. I have no issue buying compatible items but I hate supporting counterfeiting.

author: sairfan1
author_rank: Frequent Contributor
timestamp: October 05, 2022, 02:44:15 pm
content: This is quite possible they are sold in China with different part number, some people buy them and change the part number to make item more attractive to buyer.

author: edavid
author_rank: Super Contributor
timestamp: October 05, 2022, 07:54:42 pm
content: Quote from: sairfan1 on October 05, 2022, 02:44:15 pmOf course it is, but it's weird that this has been going on for years and no one has managed to identify the China maker or part number.Hmm, LCSC lists MAX7219 clones made by "XINLUDA", "HGSEMI", and "HTCSEMI". Maybe that solves the mystery.https://lcsc.com/products/LED-Display-Drivers_11285.html?keyword=7219

author: josuah
author_rank: Regular Contributor
timestamp: October 22, 2022, 12:49:48 am
content: Finally a job that is cheaper with an ASIC than with a tiny MCU!https://fr.aliexpress.com/item/1005003822582905.htmlis $0.04 per chip!You can get it from more reputable provider as well (i.e.: for non-hobby use)https://lcsc.com/search?q=TM1650And you can use it for keyboard input as well: freeing a lot of pins!https://www.utmel.com/components/tm1650-led-drive-control-datasheet-pdf-circuit-and-pinout?id=849In fact, the whole LCSC listing is more interesting than American branded chipshttps://lcsc.com/products/LED-Display-Drivers_11285.htmlNone of the provider listed on Octopart cover the low-end corners of the market, for which Aliexpress, and lcsc.com will feature the lower-end Chinese-made chips.