The I2C IO Card for ESP-12E I2C Base Card is another expander card for the ESP-12E I2C Base Card Project. This PCB is an address-selectable I2C module with two relays and six (6) GPIO pins, all driven from a single PCF8574 running at 3v. The relays are optically isolated, and generous mains isolation cutouts were provided to reduce the possibility of mains voltage tracking. A jumper to enable/disable the i2c pullup-resistors is also provided on the PCB.
The relays are powered from a single LDO regulator, accepting 12v DC from the 2x20pin female header on the bottom of the card. 3.3v and ground should also be applied to the card at the 2x20pin header.
It is worth mentioning that this circuit does not contain level converting circuitry and that the i2c bus thus runs at 3.3v to be compatible with ESP chips.
It is possible to use the card with other processors if the appropriate level converters are used on the i2c bus.
The Schematic
Manufacturing the PCB
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