The rev A board is ready to order
Six schematic sheets, a four-layer board of about 113 × 95 mm, zero ERC and DRC errors, and three review rounds before the first prototypes.
The first revision of the UPAN Core board is routed and checked. It is the board for both order codes: UPC-D with the built-in driver and UPC-S for an external Step/Dir driver. The two differ only in which parts are fitted.
What is on it
- A motion MCU (STM32G431) that makes the steps, runs the ramps and checks every limit.
- A network module (ESP32-C6) for Wi-Fi 6, Bluetooth LE and the local API.
- On UPC-D, a TMC2160 driver with external MOSFETs for 1.4–5.6 A peak.
- Step/Dir outputs for an external driver, an encoder input, two 24 V inputs, two outputs, limit switch inputs and a hardware stop input.
- USB-C for a PC and a second USB-C socket for the module bus (CAN-FD). It is not a USB port.
The schematic has six sheets and 199 footprints. The board has four layers: signals on the outside, ground on one inner layer, and the motor supply and 3.3 V on the other.
Checked, not just drawn
The schematic is generated from a description in code, so it can be rebuilt and compared at any time. Electrical rules check: 0 errors, 0 warnings. Design rules check: 0 violations, 0 unrouted nets, 0 differences between the board and the schematic.
Before ordering, the board went through three review rounds. They changed real things:
- The braking resistor switch is gone. Measurements on the prototypes will show whether the supply needs it, and the documentation now says to keep the supply at 52 V or below.
- The stop input is called what it is: a hardware stop input, not a safety-rated emergency stop. An emergency stop is a function of the whole machine, with a safety relay and a contactor.
- ESD protection on the Step/Dir lines and a few pull resistors so that nothing switches on while the MCU resets.
What comes next
Ordering the first batch from the assembly house, then bring-up: measuring gate voltages, ripple on the motor supply, heat on the current shunts and the crystal. The firmware of the motion MCU already runs on a PC with its tests and builds for the board; the hardware layer comes next.