https://www.ebay.com/itm/404204890868

No clue.

• SMA female for GNSS Ant
• 10/100 RJ45
• DC 5V input (5.5mm/2.1mm) - Marked 1A, but I haven't measured the device pulling more than 200mA
• OLED screen - blue - 128×64 pixels. Standard i2c module.

Two 10 pin phoenix-style terminal blocks, marked COM A (left) and COM B (right). The pinouts are very strange. The first 8 pins of COMA all run to the pad marked A+ on the RS485 module. The first 8 pins of the COMB block all short to the pad marked B- on the RS485 module. The last two pins on each module are also the same - pin 9 goes to the GNSS PPS pin, and pin 10 goes to the ground pin on the output side of the RS485 module (NOT the board ground!).

I think the idea is that you could run this thing to eight different systems over RS485?

COMA

1. A+ on RS485 module
2. A+
3. A+
4. A+
5. A+
6. A+
7. A+
8. A+
9. PPS
10. RS485 GND

COMB

1. B- on RS485 module
2. B-
3. B-
4. B-
5. B-
6. B-
7. B-
8. B-
9. PPS
10. RS485 GND

• One button: Marked SW-PB, pulls the 3v3 rail of the LDO to ground through a 10k resistor
• One LED: red power LED hanging off 3v3 thru 1k resistor
• Red TX/RX LEDs on the UART-RS485 board

• JP10 - 1×3 - GND | Pin 18 of GNSS (reserved???) | Pin ## on MCU - unpopulated
• JP1 - 1×4 - R/T | R/T | GND | 3v3 - populated - suspected MCU UART
• JPB - 2×3. First row is marked 5 on the left side, second row is marked 6. Right pins are marked 1 and 2, top and bottom, respectively. Middle pins are presumably 3 and 4, top and bottom. Pins 1 & 2 are 3v3. Pins 5 & 6 are GND. One jumper is present bridging “3” and 5. Unknown what “3” and “4” connect to.

• GNSS - AT6558 R-5N-32-E2 based, likely ATGM336H5N-31? - No silkscreen mark - maybe underneath?
• MCU - CH32F103 - STM32 “bluepill” clone - Marked T32
• NUC - WIZNet W5500 10/100 SPI - Marked U5
• EEPROM - FT24C16A 16Kbit i2c - Marked IC15
• ?????? - R8025 E R41 72 - Marked RX1
• 3v3 LDO - AMS1117 3.3 - Marked U1
• UART to RS485 module mounted on board - Marked T4

• Entirely hand-assembled
• Small heatsinks mounted to the GNSS, MCU, and NIC - absolutely not needed
• PPS from the GNSS is not connected to the MCU anywhere as far as I can tell. NTP server performance will suffer accordingly.
• OLED screen mounted perpendicular to the board via a female header sitting flat is very clever!