The original circuit diagram of the module, borrowed from the web, is shown below. As indicated, the GPS modules are based on the u-blox NEO-6M GPS engine. The type number of the NEO-6M is ...

The heart of the build is a NEO-6M GPS module which features a dedicated pulse per second (PPS) pin. The ESP8266 combines the timestamp from the GPS messages and the PPS signal to synchronize ...