Strip-Board Motor Driver

Knocked up a design on strip-board using a DOIT ESP-12E and a PCF8574 (and two DVR8825s):

(The above image should be re-scaled 32% for 1 to 1 printing.)

I am wondering about the SD* pins whether they can be used (I suspect they are used to access the flash memory?). Hard to find out but I suspect not (at least not easily).

I squished the two HC-SR04 echo lines onto P7 of the PCF8573 using a diode NAND gate. Had to make a 5v to 3.3v voltage translation anyway (the HC-SR04 is 5v). Added a 7805T between the Motor Supply Voltage and the EPS-12E voltage input to protect the ESP-12E from back-EMF (I am sure the 7805T can deal with the back-EMF better) and to power the HC-SR04s.

I read that the EPS-12E Arduino core does not support PulseIn() so I will roll my own using the PCF8574 interrupt line and the microsecond timer.

The EPS-12E SDA/SCL pins are programmable but I have used the defaults. So the pins are:

D3 I2C Interrupt (D0 is the built in LED)

D1 I2C SCL

D2 I2C SDA

The address of the PCF8575 is 0x20 (all the PCF8574 address lines are low).

I read the supported I2C clock frequency is up to 450 kHz so plenty fast for my application.

Need to let the "dust settle" on the design and double check before assembly (tomorrow?).\

AlanX