2.7 KiB
ESP32 Serial Swiss Army Knife
Universal wireless serial adaptor firmware for the ESP32-S3.
Initial hardware target
- ESP32-S3-DevKitC-1-compatible development board
- ESP32-S3-WROOM-1-N16R8 module
- 16 MB flash
- 8 MB octal PSRAM
- Adafruit MAX3243 full-pinout RS-232 breakout, product 5988
The current firmware is a command-driven Phase 0 hardware-characterization harness. It validates the MAX3243 breakout, its three drivers, its five receivers, valid-signal detection, active-low shutdown, and UART1 loopback before development of the wireless serial firmware begins. Tests run only when explicitly requested at the console; booting the board does not start an electrical test.
Hardware wiring
See wiring.md for the hardware profile, GPIO assignments, loopback diagrams, safety notes, and the recommended test sequence. The initial profile covers the ESP32-S3-DevKitC-1 N16R8 and the Adafruit MAX3243 full-pinout RS-232 breakout.
Build
pio run
Upload and monitor
Connect the board's USB-to-UART port, then run:
pio run --target upload
pio device monitor -b 115200
The firmware starts an interactive console on UART0. Type help to display command descriptions. The Phase 0 commands are:
status
transceiver <enable|disable>
drivers <tx 0|1> <dtr 0|1> <rts 0|1>
loopback-a
loopback-b
valid-test
uart-loopback <baud> [8N1|8E1|8O1|8N2|7E1|7O1] [bytes]
uart-suite
cts-flow-test
rts-flow-test
uart-loopback defaults to 8N1 and 256 bytes. Its accepted payload range is 1–512 bytes. uart-suite covers 300 through 250000 baud and all supported frame formats. cts-flow-test verifies transmit gating and exact resumption, while rts-flow-test uses UART2 as an internal traffic generator to verify automatic receive backpressure. Follow the command-specific loopback wiring in wiring.md before invoking any test.
The onboard RGB LED reports the most recent test-harness state:
| Color | Meaning |
|---|---|
| Blue | Idle; waiting for a command |
| Yellow/orange | Test running |
| Green | Last test passed |
| Red | Last test failed |
This hardware profile uses the onboard RGB LED on GPIO48. Official ESP32-S3-DevKitC-1 v1.1 boards commonly use GPIO38 instead, and compatible boards or clones may vary. A different board revision requires an adjusted board pin profile before running this firmware.
License
This project is licensed under the GNU General Public License version 3 only (GPL-3.0-only). This is compatible with using the GPLv3 releases of wolfSSL and wolfSSH later. Third-party components remain subject to their respective licenses.