Portsdown 4 GPIO Connections

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RPi 4 GPIO pin out

GPIO-Pinout-Diagram-2.png

  • Note the RPi4 (only) can be powered with 5v directly on to GPIO 2 and 4.

GPIO Connections for the Portsdown 4

Due to a reassignment of the GPIO pins on Raspberry Pi4, the connections are different to previous generations of Portsdown.

There are 2 GPIO pins that have changed for the RPi 4. The important one is the Band LSB (or D0) which has moved from pin 28 to pin 32.
Pin 32 is available on the GPIO breakout board as the "I" pin which is pin 2 on J03. More details here: Media:PORTSDOWN INTERFACE SCH.pdf
The other changed pin is the LE line for the ADF4351 (was on 27, now pin 33) which is only used if you are using an ADF4351 for the Portsdown Signal Generator.  So, generally no need to worry about this one. This isn't true if your Portsdown has an attenuator card fitted! Move the LE wire with its 1 K ohm resistor to the Q terminal.

The Portsdown 4 GPIO Connections are defined here: Portsdown 4 GPIO Connections.

List of GPIO connections

Pin No BCM No Wiring Pi RPi Pri RPi Alt0 Primary Use Secondary Use Notes & GPIO breakout board connections
1 - - 3.3v - - - -
2 - - 5v - - - -
3 2 8 GPIO 2 SDA1 I2C Control MCP3002 Data in -
4 - - 5v - - - -
5 3 9 GPIO 3 SCL1 I2C Control MCP3002 LE -
6 - - 0v - - - -
7 4 7 GPIO 4 GPCLK0 Band D2 (T) Langstone band D2 Label 7 on J07. "T" on 8 band boards
8 14 15 GPIO 14 TXD0 ADF5355 LE Elcom, Nort SLO and AD9850 LE For Sig Gen
9 - - 0v - - - -
10 15 16 GPIO 15 RXD0 Atten LE - Label 10 on J07
11 17 0 GPIO 17 FL1 - Langstone PTT Demand in Active low
12 18 1 GPIO 18 SPI6_CE0_N Transmit Demand Langstone CW Key in Label 12 on J07
13 27 2 GPIO 27 SD0_DAT3 "Active" LED - Active high. Label LED on J06
14 - - 0v - - - -
15 22 3 GPIO 22 SD0_CLK Shutdown Button - Active high. Label PB on J06
16 23 4 GPIO 23 SD0_CMD Band D4 Langstone band D4 -
17 - - 3.3v - - - -
18 24 5 GPIO 24 SD0_DAT0 - Langstone band D5 -
19 10 12 GPIO 10 SPI0_MOSI - Langstone band D6 -
20 - - 0v - - - -
21 9 13 GPIO 9 SPI0_MISO - Langstone band D7 Set lo for P'down, hi for L'stone
22 25 6 GPIO 25 SD0_DAT1 Band D3 Langstone band D3 -
23 11 14 GPIO 11 SPI0_SCLK - - -
24 8 10 GPIO 8 SPI0_CE0_N - - -
25 - - 0v - - - -
26 7 11 GPIO 7 SPI0_CE1_N - Noise source Battery Test Load Switch
27 0 30 ID_SD SDA0 (was ADF4351 LE) - DO NOT CONNECT
28 1 31 ID_SC SCL0 (was Band D0) (was Langstone band D0) DO NOT CONNECT
29 5 21 GPIO 5 GPCLK0 spi clock - Label CLK on J04
30 - - 0v - - - -
31 6 22 GPIO 6 GPCLK2 spi data - Label DAT on J04
32 12 26 GPIO 12 PWM0 new Band D0 new Langstone band D0 Band select LSB. Label I on J03
33 13 23 GPIO 13 PWM1 new ADF4351 LE - Label Q on J03
34 - - 0v - - - -
35 19 24 GPIO 19 SPI6_MESO Band D1 Langstone band D1 Band Select MSB on J05
36 16 27 GPIO 16 FL0 - - SR select LSB D0 on J02
37 26 25 GPIO 26 SD0_DAT2 - - SR select NSB D1 on J02
38 20 28 GPIO 20 SPI6_MOSI - D-A LE SR select MSB D2 on J02
39 - - 0v - - - -
40 21 29 GPIO 21 SPI6_SCLK TX LED/PTT Drive out - TX LED J05

Note that the GPIO pin names are markedly different from the RPi 3B. Each pin on the RPi4 GPIO can be referred to in many ways: its physical pin number, the Broadcom I/O number, the Wiring Pi number or the primary or alternate names. Source for GPIO designations was the Raspberry Pi 4 Model B datasheet.

Note that no connections should be made to GPIO Pins 27 and 28, otherwise the RPi might get stuck on the Rainbow Screen at boot. Previous connections to these pins are being moved to other pins 32 and 33.

J0x terminal block identities relate to the BATC GPIO breakout PCB from the club shop..

Unused Willow breakout boards may work with Portsdown 4 because they needed extra connections to pins 27 & 28 on Portsdown 2018. These aren't required on P4 as noted here.

Pins 36, 37 & 38 are still connected for extra DO, D1 & D2 connections. These are used with the 2-way RF Switch - F-M port of which is connected to the Pluto. All 3 lines are sent to logic high (3.3V) in Portsdown 2019 / 2020 and in the 4 on transmit and this switches in the Lime Mini.