Working
RS485 via UART0 (Drive GPIO5 HIGH to enable output to A0/B0)
Green LED (GPIO4)
IO0-IO3 (GPIO 17, 18, 27, 22), all 5V logic
Ask for help
Let me know if this document contains something, what not should be public!
If you have such a board and have details about RTC, serial, DCDC, please let me know!
If you are able to use serial or RTC from software, please let me know it!
Hardware details
The main components are:
- U1 AHHCY6 DCDC regulator
- U2 1117 3,3Volt Low Dropout Voltage Regulator
- U6: TS3A24157 2-Channel SPDT Analog Switch
- U7: SP3483, SO08, 3.3V Low Power Slew Rate Limited Half-Duplex RS-485 Transceiver
- U3: WCH CH432T SSOP20 SPI dual UART
- Y1: 22.1184 MHz Quarz (for U3)
- U8 Sipex SP2323EE True RS232 Transceiver
- U9: SP3483, SO08, 3.3V Low Power Slew Rate Limited Half-Duplex RS-485 Transceiver
- U4 Epson RTC R8010, I2C und 2x IRQ
- Q2: SOT23 702: 2N7002, N-Channel Mosfet
- Q1 NPN Transistor 1AM = MMBT3904L
- SS34 40V 3A Shottky Diode
- U12 TXS0102DCUR FE NZ dual Level shifter (3.3V <-> 5V)
- Diode CG_ TVS Diode 28V
- BAT54C SOT23 Marking TL3
- ESD Diode Marking AC: PESD5V0L1BA, Low capacitance bidirectional ESD protection diode SOD323
The IO Pins (on green terminals: 5V via 2x FE NZ) are:
- green LED: GPIO4
- IO0: GPIO17
- IO1: GPIO18
- IO2: GPIO27
- IO3: GPIO22
RealTime Clock:
- RTC SDA: GPIO2
- RTC SCL: GPIO 3
- RTX IRQ1: GPIO6
- Software:
2channel SPDT switch:
- COM1: UART0 TX
- COM2: UART0 RX
- IN1+IN2: via R34 to GPIO5
- NC1+NC2: not connected (via R44 + R45 to second channel of U8, option: move FB1+2 to FB3+4 and remove R48, R50, R53)
- NO1+NO2: SP3483 (RS-485) to B0/A0
- Software:
- set correct GPIO5 state
- use Raspberry UART with any modbus library
CH432T SPI DUAL UART (RS485 and UART via Raspberrys SPI Interface and CS0)
- INT: GPIO7
- SCS: GPIO8
- SDO: GPIO9
- SDI: GPIO10
- SCK: GPIO11
- Software:
- port 0 (RS485): GitHub - DFRobot/DFRobot_CH432T_raspberrypi
- port 1 (UART): ?
The terminal blocks have the imprints
- Power: 2EGT-5.08
- Data: 15EGT-3.5
I found one of those on the web. I'm using the wide-range DC input to power a RPi 4B, and so far had no trouble with the Pi in regard to that.
The company which is given on the board has no information whatsoever on this board on the web. Also, the ISG-502 doesn't pop up anywhere on rockemb.com. I tried various archive pages and I found: nothing.
I really would like to use the RTC, and find out more what these things did, and how I could re-purpose it.