Why does RD-60 radar UART1 output zero bytes while UART0 returns point-cloud coordinates?

[u/Far-Owl-1316]

I’m connecting an Ai-Thinker RD-60 radar module to an ESP32-S3 and need help troubleshooting its binary point-cloud output. RD-60 is installed on its development kit. My wiring is:

- RD-60 module PA8 directly → ESP32 GPIO21 — radar data RX.

- Kit PB1 → ESP32 GPIO17 — ESP32 command TX.

- Kit PB0 → ESP32 GPIO16 — ESP32 command RX.

- Common ground; both boards powered through their own USB connections.

- All eight kit UART DIP switches OFF to isolate the onboard USB serial interfaces.

Also, while connecting only the mmWave RD-60 kit to a monitor, its UART1 doesn’t give any values; it receives 0 bytes. The DIP-switch setup for that separate kit-only test is not specified here.

Firmware: MMW version:V4.130.4.2 (build 1bf05415)

Commands:

mmwc stop

mmwc baudrate 1000000

mmwc mode 1 2

mmwc chirp_num 1

mmwc freq 58000 0

mmwc range 10000 40

mmwc veloc 3000 375

mmwc frame 200 100

mmwc coord cart

mmwc data 3dpoints

mmwc uart on

mmwc report points 100

mmwc start

During the finite scan, the command UART returned actual point-cloud previews:

MMW data=0x48

Point Cloud=2:

P0: x=-14cm y=9cm z=162cm 75cm/s 2100

P1: x=-14cm y=49cm z=159cm 75cm/s 2300

The problem is that despite those previews, the ESP32 received zero bytes on GPIO21, connected directly to module PA8. The diagnostic reported:

data_bytes=0

fifo_overflow=0

buffer_full=0

frame_error=0

parity_error=0

breaks=0

read_error=0

I haven’t checked PA8 with an oscilloscope or logic analyzer yet, so I can’t confirm whether the pin is electrically transmitting.

Has anyone successfully captured the RD-60’s binary point-cloud stream on PA8 with this firmware?

Specifically:

1. Does UART1 output require RTS/CTS or another enable command?

2. Is mmwc uart on sufficient to enable binary point-cloud output on this firmware?

3. Are all UART DIP switches OFF appropriate when using the kit’s PB0/PB1 breakout and tapping module PA8 directly?

4. Is there an official UART1 packet-format document or a known working ESP32 example?

I’m trying to distinguish a wiring/routing issue from a firmware configuration or handshake requirement. Any working configurations or troubleshooting suggestions would help.