Each PIC connects to an enhanced SPI port on the RPi4, but an RPi2/3 has only one of these ports. By sharing the single enhanced SPI port on an RPi2/3, it's possible to transfer data from the PICs alternately rather than simultaneously. Throughput is reduced, but should be a minimum of 10M bits/s, which is enough to view four copies of the beacon at once.
I'm running my WH on an RPi2 v1.1, which is the least capable of the 4 core RPi's. I've increased the GPU memory by 512MB, to simulate an RPi with only 512MB of total ram and it works fine. It should be possible to use an RPi3A+ which has 512MB ram and no Ethernet, over 5GHz WiFi, but I haven't been able to test that yet. This would be useful, as RPi3A+'s are currently available. It does present the problem of WiFi in a metal box.
The only hardware mods required are to connect 2 pins on PIC_A to PIC_B.
One snag is that the RJ45 and USB connector positions were swapped over on the RPi4. The connector opening on the panel would need to be enlarged slightly. Alternatively, some nuts could be fitted on the F sockets inside the case to back the pcb away from the panel. In this case, the power plug may not be able to reach the socket, but the body of the plug could have an annulus removed to give it more reach.
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- whpanel1.jpg (1.41 MiB) Viewed 3345 times
- whplug1.jpg (28.29 KiB) Viewed 3345 times
It would be useful to have a few people beta testing it. A new SD card is required. At this stage, the installation is not completely automatic, so some knowledge of the Linux command line and editing files would be useful. Please comment here and I'll send you a PM.
Thanks to G1LWX for the photos and doing the initial testing.
Brian
