Luz

luz

An experiment in USB-C power delivery.

This repo contains printed circuit board fabrication files and firmware sample for a basic USB-C power delivery "trigger board" with an accompanying ESP32.

Hardware

The CYPD3177 IC is used to negotiate power contracts with USB-C power supplies, and communicates with the onboard ESP32 via I2C for control and monitoring.

Once the required power delivery contract is successfully negotiated, the ESP32 may control two MOSFET channels to switch power to two different loads. The original use case is to deliver 12 V @ 3 A to LED strips, but any load up to 3A and 20V may be used in principle.

Main Components

• CYPD3177 USB-C PD controller
• ESP32-WROOM-32
  • For this prototype I used this older module since I still have a bunch of them around.

Software

The CYPD3177 is configured during runtime via I2C. I implemented the cypd3177 component in an ESPHome fork (at rbaron/esphome/cypd3177).

In this repo there are sample yaml files under ./code/esphome that uses the cypd3177 as an external component.

To configure a power delivery contract, set up the cypd3177 component in ESPHome as for example:

cypd3177:
  interrupt_pin: GPIO23
  voltage: 9000 mV
  current: 1000 mA

USB-C Power Delivery Support & Maximum Power

The CYPD3177 supports USB-C PD 3.0, but unfortunately does not support Programmable Power Supply (PPS) contracts. The board is a prototype, mostly for learning, designed to handle a maximum of only 3 A.

USB-C PD 3.0 mandates support for a few standard fixed power profiles, namely providing 5 V, 9 V, 15 V and 20 V. Some USB-C PD sources may also support 12 V. Enabling logging for the cypd3177 component in ESPHome will show the power profiles supported by the source. For example:

16:08:41.416 -> [I][cypd3177.pdo:059]: Fixed PDO: 5000 mV, 3000 mA
16:08:41.416 -> [I][cypd3177.pdo:059]: Fixed PDO: 9000 mV, 3000 mA
16:08:41.416 -> [I][cypd3177.pdo:059]: Fixed PDO: 12000 mV, 2000 mA
16:08:41.416 -> [I][cypd3177.pdo:059]: Fixed PDO: 15000 mV, 2000 mA
16:08:41.416 -> [I][cypd3177.pdo:059]: Fixed PDO: 20000 mV, 1500 mA
16:08:41.416 -> [I][cypd3177.pdo:066]: Augmented SPR_PPS PDO: 3300 - 11000 mV, 3000 mA