Why did I make it?

Development tools should be reliable and adapted to the type of work you do. I was tired of USB to serial adapters ordered from Ebay/Aliexpress that were using counterfeit chips with inferior performance and were not providing the full functionality I needed.

What makes it special?

VoltLink revB features a Silabs CP2102N USB to serial converter chip sourced from a reputable distributor ensuring the highest performance and reliability. The chip is capable of up to 3M baud rated which translates to faster upload speeds for those oversized binary images that we are dealing when programming modern a SoC like the ESP32.

On the USB side connection is made via USB Type-C connector. This means one less cable type you need to keep around and also a reliable and sturdy connection which should ensure VoltLink will last more than the old micro-usb connectors.

VoltLink features auto-reset circuitry for the ESP32 by automatically switching the EN and IO0 signals in the correct sequence to enter bootloader mode. You just hit "Upload" in your IDE and the board takes care of the rest. You don't have to mess around with manually pressing a reset switch. In adition to that, it also implements a fix for the dreaded "A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header" error as discussed in Voltlog #357.

For universal compatibility Voltlink features 0.1 inch header connections but also brings a new JST-SH 1.0mm pitch slim connector that brings space-saving advantages to your designs. By using the included JST-SH pigtail you are able to quickly connect to your target. If you would like to order more JST-SH connectors or pigtails check out these links: Link1, Link2, Link3.

For increased reliability VoltLink features ESD & resettable over-current protection on the input side because accidents can happen during development, but these protection features will help to keep your circuit safe.

Due to it's on-board 3V3 500mA regulator, VoltLink is capable of powering your downstream device while programming it. You no longer have to supply separate power to your ESP32 while flashing firmware.

Other Design features

The PCB was designed as a double sided board with surface mount components installed on the top side. The design is Open Source so if you would like to build your own I encourage you to grab the source files from the Github repository linked below.

There are four M3 mounting holes placed in the corners of the board so if you wish to design & 3D print an enclosure for this board just follow the mechanical drawing included below.

Compatibility

Because this adapter uses the Silabs CP2104 / CP2102N chip it should be automatically detected & installed under Windows, Mac and Linux however some older versions of the operating systems might require you to install a driver manually.

Optionally you can choose to get a custom 6 pin Shelly programming adapter for using the VoltLink to power and flash Tasmota or ESPHome safely onto your Shelly relays. To avoid any risk of injury and damage to equipment, before connecting the VoltLink to your Shelly relay, make sure the relay has been removed from your installation and is fully disconnected from mains power. VoltLink will provide power to your shelly relay.

Check your specific Shelly relay model for pinout information and connect the programming adapter accordingly. (this adapter has been tested and is confirmed working with Shelly 1Plus PM, Shelly 2.5, Shelly Dimmer 2, Shelly EM, Shelly Plus 1PM, Shelly Pro1, Shelly Pro2, Shelly Pro1, Shelly Pro2).

The newer Plus series from Shelly has an extra pin which should be left unconnected, check the pinout!

Shelly Plus 2PM has a different pinout so you can't just plug in the adapter for a plug & play flashing experience.

The adapter comes with its own JST pigtail to be used when connecting to VoltLink.

Specs

• USB 2.0 over Type-C connection.
• Input voltage: 5V.
• Over-current protection: PTC 0.75A.
• ESD protection: data lines & VUSB protected with ESD diodes.
• Onboard regulator: 3.3V 500mA max!
• IO voltage: 3.3V - 5V (CP2102N pins are 5V tolerant).
• Baud rate: up to 3M baud.

What you get with your order

You will get 1 x VoltLink USB to Serial Adapter, 1 x 0.1 inch 6 pin header and 1 x JST SH 6 pin pigtail. Optionally you can choose the custom Shelly programming adapter to be included (in 1 or 2 pcs qty).