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NMEA3WIFI (2022) - SMD, TH and KIT

Posted: Tue Mar 08, 2022 1:16 am
by Luis Sa
(please also read the following topic as the KIT/TH version has been upgraded in October 2022)

The Nmea3Wifi multiplexer was developed in collaboration with Richard Clutterbuck (username in this forum is dagnall) to be used in a SeaTalk1 bus. In this post I describe some technical details of the multiplexer. Normal users do not need to read this as everything concerning the operation of the multiplexer is shown here.

The multiplexer is available in versions built with SMD (Surface Mounting Devices) and TH (Through-Hole) technologies. It can be supplied in 3 versions:
  • Nmea3Wifi SMD
  • Nmea3Wifi TH
  • Nmea3Wifi KIT
All versions are identical in terms of functionality and software. The TH and KIT versions are also identical in terms of hardware. The obvious difference is that the KIT version is assembled by the user. In all versions you can use a USB cable to receive and transmit data from and to a computer. This USB cable can also power the multiplexer so that you do not need to supply 12V to the multiplexer (in the case you do not use the SeaTalk functions). Both the USB cable and the 12V supply from a battery can coexist. If you use an USB cable the top cover box may not fit, except if you cut an hole on the top cover in the case of the SMD version. Flexible USB cables can possibly be used on the TH and KIT versions. All versions use screw high quality connectors accepting cables up to 1.5mm2.


The circuit diagrams of the multiplexers can be downloaded from the links at the bottom of this post.


(please also read the following topic as the KIT/TH version has been upgraded in October 2022)

The remaining part of this post is addressed to the builders of the Nmea3Wifi KIT. Kits are supplied with the original Instruction Manual for the Nmea2Wifi multiplexer. We advise you to read that manual as there are many common aspects between the Nmea2Wifi and the Nmea3Wifi Kits. Basically the Nmea3Wifi kit uses a different processor. Instead of the ESP8266 module, the Nmea3Wifi kit uses an ESP32 module developed by Vela Navega. In the following we show the relevant differences to the referred to Instruction Manual. The parts list is as follows:


The PCB (Printed Circuit Board) is shown here (colour could be green):


and the some parts in this KIT (with instructions) are shown in the following picture:


Note that the diodes, LEDs, R4 resistor array and ICs need proper orientation. The diodes have a bar that indicates the cathode. You need to insert them so that the bar that exists in the body of the component coincides with that shown on the PCB. The LEDs have 2 terminals (anode and cathode). The cathode terminal wire is shorter than that of the anode and should go on the lower hole of the PCB orientated as in the picture above. Resistor arrays R2 and R4 have a dot printed in their bodies. The pin near the dot of R4 should go on the hole whose pad is quadrangular. Resistor array R2 can be mounted either way. As for the ICs please follow this picture:


The following pictures (they refer to the Nmea4Wifi multiplexer but they are general) will also give you some ideas on how to assemble the KIT.


Finally note that the ESP32 module is already flashed. It could be the case that the firmware version supplied with the module is not the most recent one. If that is the case it is very easy to do an update.

Regards, Luis

NMEA3WIFI - TH and KIT after October 2022

Posted: Fri Nov 04, 2022 4:38 pm
by Luis Sa

I have made a change in the hardware of the Nmea3Wifi multiplexer. The interface to the SeaTalk1 bus that was based on a 2731 optocoupler is now built around 3 transistors. This only applies to the TH and KIT versions. The hardware of the SMD version remains the same. KIT builders should read the previous topic and take into account the differences described next. The new PCB is now like this:


Please note LEDs L1 up to L5. When inserting them on the PCB make sure that the longer terminal of each LED will go on the top pad (in relation to this picture). The list of components is this one:


The new schematics is attached. The ESP32 module is already flashed.

Regards, Luis