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 'outputbytes' 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.