@ WaveyDipole
I can't see the numbers on the TO-220 device, but I presume that since the Pro Micro has no on-board 3.3V regulator, that you had to use an external regulator?
Indeed, it is a LF33 3,3V regulator for the ESP8266.
Do the 4 resistors form a pair of dividers to convert the serial TTL level signal on the Arduino to 3.3V level for the ESP8266?
Not quite. Two of them are pull-up resistors as two of the ESP8266 inputs need to be pulled up, e.g. the reset input.
The other two are 470 Ohms serial resistors in the RX and TX UART lines. These are indeed for overvoltage protection of the 3,3V ESP driven by the 5V Arduino.
They just do current limitation. Voltage limitation is achieved by the input clamping diodes inside the ESP chip. As I never know, which line is actually the 5V line that needs the limitor resistor, I simply add a resistor to each line to be on the safe side. It won't do any harm if it is not needed. It is the simplest way of level adaption. Btw, it is safe to drive a 5V input with 3,3V as the switching threshold is 2,5V, giving 0,8V of margin which I consider as sufficient.
I have for some time been working on my own version of the TCP to UART concept...
This sounds like a very comfortable solution. I would be very interested to give it a try. Where can I find the code?
And another thing:
May I propose a small update to the Mega32U4 config code:
/*** MEGA 32U4 based boards (Micro, Leonardo) ***/
#elif __AVR_ATmega32U4__
/*** Board/layout selection ***/
#define AR488_MEGA32U4_MICRO
/*** Serial ports ***/
// Comment out if using RXI, TXO pins
#define AR_CDC_SERIAL
// The Mega 32u4 default port is a virtual USB CDC port named 'Serial'
#ifdef AR_CDC_SERIAL
#define AR_SERIAL_PORT Serial
#else
#define AR_HW_SERIAL
#define AR_SERIAL_PORT Serial1
#endif
The added preprocessor code simplifies switching between CDC and HW serial, so acutally commenting out the indicated line will suffice to switch.
@ Gerhard_dk4xp
Hi Gerhard, nice to hear from you again.
I hope, the Jalapenos grow well on your new balcony.
Best regards,
Tom