Usable Input/Output pins

[cermilk.aep]

Hello!

So I have been researching very intensively about the ESP32-S3 Mini 1 N4R2 module and could not find a proper pinout. What pin is the safest to use to control my 8 relays, and all those 8 pins must be LOW at startup. May I know what pins have low-level glitches and high-level glitches, strapping pins, and what are not recommended to use for outputs?

my target config:

8 relays, total of 8 pins (MUST BE LOW AT STARTUP).
12 pins are just used to drive segment display (dont care if output pin glitches for a moment since it is harmless).
4 input pins for push button. BOOT and EN is not counted. pins must not interfere with boot process
2 input pins for optocoupler; pins must not interfere with boot process
GPIO 1 is used for voltage measurement.

I am very sorry for my grammar. Thankyou very much!

[MicroController]

what pins have low-level glitches and high-level glitches

ESP32-S3 Series Datasheet v2.1, page 18: "Table 2-2. Power-Up Glitches on Pins"

The rest of the pins' 'features' are also scattered inside that document.

[simonjo]

I think the safest bet is using a PCA9634 8 channel led driver chip, uses I2C and it is fully programmable

I use it in combination with 4K7 resistor to drive an MMBT2222A to drive 24V relays RT114024 from Schrack or G2RL-1 from Omron

[MicroController]

"an I2C-bus controlled 8-bit LED driver optimized for Red/Green/Blue/Amber (RGBA) color mixing applications" may be a little overkill. Any other, more simple/cheaper I2C IO expander would also do.

[simonjo]

@MicroController
Which other part would you suggest?

PCA9634 is 8 output, you can drive each channel individual: OFF, FULL ON, PWM or PWM modulated on group frequency by setting 2 bits per channel. You can also choose for open drain or totempole output, normal or inverted.

For 24V relays we use the totempole + inverted setup, turning a relay on follows a sequence of FULL ON, ~50ms timer and then we move to the PWM driving to reduce power on long term.

Nothing fancy about it, nor overkill and especially when you need 8 outputs with guaranteed off outputs on power-on

[MicroController]

PCF8574 seems to be pretty common (8 I/O, no PWM), or MCP23017 (16 I/O).