Max digit count locked at 4 + esp8266 support

[einarav]

from 7segment_gpio.h line 33:
constexpr uint8_t max_digit_count = 4;
Cannot initialize more digits because of this limit.

I also tried using this with esp8266 and that did not work, are you planning to implement support for that?

[asergunov]

Hello. The hardcoded limit looks one char fix. You more than welcome to open pull request.

For the esp8266 the problem I guess is the way timer interrupt setup. I'll be happy if you have a look.

[asergunov]

Just curious did you figure out pins to use for display on esp8266?

• D1, D2 fine
• D5, D7 (spi) fine
• D3, D4 should be HIGH on boot
• TX should be HIGH on boot
• D0 becomes HIGH on boot
• D8 should be LOW on boot

Gives me 9 pins so 2 digits without dot or one digit with dot max.

Also we should figure out connection which will let it boot.

I'll be happy if you share your experience.

[einarav]

I am using a couple of SN74HC595 shift registers connected to my displays! Hot fixing the char limit on my library clone allows me to set the pins:

• [18:00:56][C][lcd_digits:333]: LCD Digits:
• [18:00:56][C][lcd_digits:336]: Digit Pin: 8 via SN74HC595
• [18:00:56][C][lcd_digits:336]: Digit Pin: 9 via SN74HC595
• [18:00:56][C][lcd_digits:336]: Digit Pin: 10 via SN74HC595
• [18:00:56][C][lcd_digits:336]: Digit Pin: 11 via SN74HC595
• [18:00:56][C][lcd_digits:336]: Digit Pin: 12 via SN74HC595
• [18:00:56][C][lcd_digits:336]: Digit Pin: 13 via SN74HC595
• [18:00:56][C][lcd_digits:336]: Digit Pin: 14 via SN74HC595
• [18:00:56][C][lcd_digits:336]: Digit Pin: 15 via SN74HC595
• [18:00:56][C][lcd_digits:340]: Segment Pin: 0 via SN74HC595
• [18:00:56][C][lcd_digits:340]: Segment Pin: 1 via SN74HC595
• [18:00:56][C][lcd_digits:340]: Segment Pin: 2 via SN74HC595
• [18:00:56][C][lcd_digits:340]: Segment Pin: 3 via SN74HC595
• [18:00:56][C][lcd_digits:340]: Segment Pin: 4 via SN74HC595
• [18:00:56][C][lcd_digits:340]: Segment Pin: 5 via SN74HC595
• [18:00:56][C][lcd_digits:340]: Segment Pin: 6 via SN74HC595
• [18:00:56][C][lcd_digits:340]: Segment Pin: 7 via SN74HC595

I still need to figure out the interrupt routine to get anything usefull displayed on the displays, I will share whenever I get closer to resolving this!

[asergunov]

That's great! Checked their code of sn74hc595 component

It performs write operation whenever single pin changed. But for display it will be nice ti change all at once:

• set OE High
• transfer all new bits
• set OE LOW to show digits

I guess you'll need to update also sn74hc595 component to change 'output_bytes_' all at once.

Or just a flag disabling gopio_write calls so you can set all the bits in state you like and write them all at once when done.

[einarav]

I was finally able to take a closer look at this, and have created a local branch with the 8 digit limit fix, but I am not allowed to create a new branch here on github to make the PR.

I'll try to add esp8266 support for GPIO, and after that with the sn74hc595. It might make more sense to fork this library with the sn74hc595 since the library has GPIO in the name?

[asergunov]

To make a PR you need to fork this repo, make changes in your fork where you can create any branch you like and make a pr to this one.

[asergunov]

We can add another 'display_type' I guess. Or make it new component even in the same repository.

But I'm not what is the best way to handle sn74hc595 changes we need.