Hijax

Serial and power mux board is ready for ordering. However before I do so, I need to wait till SD card mux board redesign is complete at least overall idea is “approved”. As previously written the major change is to switch from simple SDI interface towards SDIO one allowing full speed communication with card. This requires 8 pins thus not only mux board but also card adapter tuning. Recently idea under consideration is to move SD mux board away from stacking and make it more alike USB Mass Storage device.

Order of stacking: to make 7seg LED visible, I.e. SBC -> Blue -> Green When stacked, SBC shall be powered from this sandwich top board connector. SBC thus shall be able to switch ports, what shall be reflected on 7seg. 7seg represents the port, serial lines (RX/TX) shall be routed to. In princible via I2C we program 16bit word. Low byte is a power dsictribution, any of those bits control mosfets to power the connetced SUT SBC. High byte is split into two 4bit chunks. Low control serial port mux, high are used by blue board to connect SD card. Idea is, to be able to power all but one SUT-SBC, write data to SD card, release SD by SBC, power on specific SUT-SBC using the SD we just modifying, wait for RS232 communication to confirm booting went OK. In the meantine one can switch serial mux to other port to write something as terminal command.

Nice. But one 2x5 connector shall have long legs. To allow interconnection between boards/ stacking of them on top of SBC

I hear ZX spectrum :)

The distance between hats are about 22mm. Enough to open latch and remove / insert SD card. Having said that, now I am not able but hopefully shortly Igor could check that.

Can not recall now. I remember thinking about footprint. But also it may be this one was available at TME those days. From the other hand the cards are inserted once so way of installation is not so important. At least to me.

I have sourced that from tme.eu

Very true...

@Tido no idea what country is yours but I can suggest ... use google for searching china pcb prototyping. I have recently used easyeda service, or jlcpcb. They manufacture 5 pcs (of each board, hence 3 times 5 pcs) for as little as 2USD plus delivery. Check their site. They can also do some basic assembly (I was not using that option yet, they can have some parts at their stock, anyway you may discuss the SMD soldering only as THT is simpe one) Happens I have 4 set of boards (as I assembled one set only) and I can send those somewhere, to @Igor for example?

Well, it is Mac OS resource "garbage" you can delete it.

@Tido et all, here comes the files of the project I started but had to suspend. Firstly, as I by mistake did a short circut using the only board I have assembled. Secondly - covid syndrome (the same number of tasks at work, twice the number of meetings and no workshop entry) Anyway, latest files I have on my github. Zipped. 3 folders - 3 KiCad projects: source files, bom, other docs needed and so on. Have a fun and stay healthy! armbian-testing.zip

Small progress update - fresh photo.

Hi, My experiences with crontab @reboot is that I dropped that solution in favor of systemd services. To give you basic idea here comes a excerpt of code I put into the customize-image.sh script: cat <<EOT >|/usr/local/bin/usb3-memory-size.sh #!/bin/bash echo 1000 > /sys/module/usbcore/parameters/usbfs_memory_mb exit 0 EOT chmod +x /usr/local/bin/usb3-memory-size.sh cat <<EOT >|/lib/systemd/system/usb3-memory-size.service [Unit] Description=USB3 memory sizer Before=basic.target After=sysinit.target local-fs.target DefaultDependencies=no [Service] Type=oneshot RemainAfterExit=yes ExecStart=/bin/bash -c "/usr/local/bin/usb3-memory-size.sh" [Install] WantedBy=basic.target EOT systemctl enable usb3-memory-size.service It creates a new service that corrects the kernel setting for USB3 camera. This works perfectly fine. When such a service shall be triggered depends on your configuration. Look at the line of [Unit] section, explicitly before/after lines. For example you can force such a service to start after login prompt pops up.

Hi @lanefu, things go slowly for two reasons: problem with delivery of sdcard connectors and also lack of free time for soldering Now, after summer time period, things hopefully will go in more planned & coordinated way. If you like, I can publish design documentation right away. Or just stay tuned, I do not drop this project, so i will update in one or two weeks status.

My fault