I’ve been working some more on my 8×8 LED matrix clock. I’ve added a DS1307 RTC chip, which has to run from the 5v pin on the NodeMCU and use 10k pullup resistors between 3.3v and the SCL/SDA pins on the NodeMCU and DS1307. I’m using the Adafruit fork of RTCLib as it has better ESP8266 support and uses unixtime. I’m using this chip as I’ve got a load of them and already have a veroboard setup with the coincell and crystal.

I’ve just received one of these Wifi Witty AKA Gizwits ESP-12F boards. The board is in two parts – one part has reset/flash buttons, a CH341 UART and female headers; the other half has USB for power only, a button (which appears to be an input, not reset or flash) and male headers which take up an entire breadboard. Despite having flash/reset buttons I can only seem to program it from the Arduino IDE with the NodeMCU v1.

I’ve been playing with the LedControl library again, this time preparing my 8×8 matrices to be used as a clock, although I’m waiting for two more to arrive from AliExpress. Anyway, its pretty simple to wire them up in series, you basically use the same pinout for connecting to an Arduino as you do for connecting the matrices together – VCC, GND, DIN, CS, CLK. For my sketch, I’d prefer them to be rotated 90 degrees, so that the input/chip was on the bottom and output wires at the top (rather than left to right), so I had to edit the hex a bit.

I’m thinking of building an alarm clock next, I need something that has bright lights that can be turned on and off, as my wall clock I can’t read at night. I’m probably going to use four MAX7219 controlled 8×8 LED matrices just to display the four digits. I was thinking of a 7-segment display, but that’s a bit small. Also I’d like it to be NTP synced, so needs wifi.

I just received my NodeMCU Motor Shield to go with my NodeMCU v1 ESP12e development board and robot chassis. So the board has a bunch of screw terminals on it – A+, A-, B+ and B- to connect two motors, and then VM/GND (up to 9v for the microcontroller) and VIN/GND (up to 36v for the motors). However the mostly undocumented feature is that if you jumper the VIN/VM pins near to the power switch, you can supply up to 9v to VIN/GND and it will feed that into the motors and also into the NodeMCU’s 3.