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Mixing compute modules
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stonybo

12/23/2023, 7:33 PM
I've waited a loooong time to get CM4s for my Tp2 so I ordered two RK1 modules instead. Now the CM4s are available again. Can I mix compute modules in my Turing Pi 2, 2 CM 4 with 2 RK1s? What are the disadvantages! TIA
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terarex

12/23/2023, 10:16 PM
Yes, you can mix any compatible SoM. The TPiv2 is a loosely-coupled cluster. No particular disadvantages beyond the level of Linux support and performance of an individual module. It also depends upon your workload characteristics and how far you want to go down rabbit holes. Raspberry Pi CM4 is the most mature and best supported, but RK1 and NVIDIA Jetson Orin have better performance. CM4s are a good option for learning Kubernetes/Docker with minimum extra complexity.
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stonybo

12/23/2023, 10:20 PM
Excellent advice. I'll probably purchase a couple of CM4s and add the Rk1s later. Thanks!
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the_boom_boom

12/24/2023, 2:44 PM
theoretically the modules don't even have to be all arm based. I'm hoping to get my hands on a risc-v module at some point
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realtime3392

12/24/2023, 4:42 PM
I just got one Lichee 4A module that I'm about to start tinkering with. I've got a Milk-V Mars CM on order also.
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terarex

12/25/2023, 2:42 AM
I ordered a Lichee Pi 4A, with the LM4A module, from Amazon. Received it this week. Downloaded the latest Debian images and updated the eMMC today. The documentation is a bit out of sync and inaccurate, but it's good enough for most purposes.
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realtime3392

12/25/2023, 4:34 AM
I just imaged mine today as well.
I'm traveling for the holidays, so I used an old Intel Core2 Duo with Ubuntu 22.04 LTS installed. I haven't put the LM4A into a TPi2 backplane yet.
I'll do that in a couple of days when I get home.
I also put the latest supported Jetpack on the first of my "cheap from eBay" Auvidea Xavier AGX computers using that same setup. When I get home, I have 3 more of those Xavier AGX computers to image, and then I'll start updating the Orin NX, Orin Nano, and Xavier NX modules I have in TPi2 backplanes using that laptop.
It looks (currently) like the Jetpack preview only supports Orin targets. I had to use the latest release Jetpack to image the Xavier AGX hardware I brought with me.
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terarex

12/25/2023, 7:00 AM
I was under the impression that the LM4A wasn't compatible with the TPiv2 board. The T-Head TH1520 processor doesn't include PCIe. Sipeed has their own 7-node cluster board (LC4A). I do like the way they made the BMC (with an AllWinner D1 RISC-V processor) as a removable module.
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realtime3392

12/25/2023, 7:07 AM
I actually have their backplane, six additional LM4A modules (modules only, without the carrier), and one Lichee RV module (with 1GB of RAM, used as the BMC, as you mentioned) on order.
I was planning on comparing the pin-outs of the LM4A SO-DIMM first, before doing anything silly. 😉
Without PCIe, you'll certainly lose some TPi2, but that alone doesn't exclude hosting four of them with USB, UART, and GbE connectivity (again, assuming compatible pin layouts for the functions that are present).
Isn't that the same link I just posted two messages earlier? 😁
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terarex

12/26/2023, 4:19 AM
Doh! Yeah. Didn't read because I thought you had posted a link to the LC4A.
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realtime3392

12/26/2023, 4:22 AM
I'll make a Google Sheet when I get a chance, with side-by-side comparisons with LM4A, RK1, Jetson modules, the CM4 in an adapter, etc.
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terarex

12/29/2023, 2:59 PM
ARace has most configurations of the Milk-V Mars CM back in stock.
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