Hey
some time ago i posted a thread where i wanted to mod a CM4 Carrier board but it never happened so far
im wondering if a better idea would be to create my own carrier board... the cm4 io board schematic doesnt seem that hard but i definitely need some help to optimize things
i have some basic electronic understanding but its very limited
i started re-creating the cm4 io board but stripped down in EasyEDA, the hardest part so far seems to decide on what parts i use (quality connectors? what kind of resistors/capacitors etc...)
the cm4 io board is wired quite straight forward but im wondering if additional big capacitors could help on the power lines and near some end-devices like usb/hdmi/sdcard/gpio (something like 500-2000uF)
what should i implement to reduce noise ?
the power source will be seperated (probably some LT3045 implementation) power input will be +5V (and potentially +3,3V and +12V)
the board has:
40pin gpio
1x hdmi
1x ethernet
1x usb OTG
1x pcie (this will be used for a usb hub, like on the rpi4)
1x pinheader for some jumper settings
1x power and activity led
everything else was scrapped, its pretty straightforward specially because the usb hub will be external
How would you approach improving the cm4 io board design ? (just add more capacitors and call it a day?)
cm4 carrier board schematic (you need to scroll down): https://cdn-shop.adafruit.com/product-files/4787/4787_cm4io-datasheet.pdf
some time ago i posted a thread where i wanted to mod a CM4 Carrier board but it never happened so far
im wondering if a better idea would be to create my own carrier board... the cm4 io board schematic doesnt seem that hard but i definitely need some help to optimize things
i have some basic electronic understanding but its very limited
i started re-creating the cm4 io board but stripped down in EasyEDA, the hardest part so far seems to decide on what parts i use (quality connectors? what kind of resistors/capacitors etc...)
the cm4 io board is wired quite straight forward but im wondering if additional big capacitors could help on the power lines and near some end-devices like usb/hdmi/sdcard/gpio (something like 500-2000uF)
what should i implement to reduce noise ?
the power source will be seperated (probably some LT3045 implementation) power input will be +5V (and potentially +3,3V and +12V)
the board has:
40pin gpio
1x hdmi
1x ethernet
1x usb OTG
1x pcie (this will be used for a usb hub, like on the rpi4)
1x pinheader for some jumper settings
1x power and activity led
everything else was scrapped, its pretty straightforward specially because the usb hub will be external
How would you approach improving the cm4 io board design ? (just add more capacitors and call it a day?)
cm4 carrier board schematic (you need to scroll down): https://cdn-shop.adafruit.com/product-files/4787/4787_cm4io-datasheet.pdf
so far i found this might be good:
1. esd protection on usb/hdmi/ethernet
2. power coupling + bypass cap at each device/output (gpio/usb/hdmi/cm4)
3. power coupling caps at the power inputs (+5V, +3,3V, +12V)
4. power coupling on the 1,8V and 3,3V voltage rails of the CM4 to filter out noise
how do i go about calculating power coupling caps? can i just use some high value like 680uF (+0,1uF for bypass caps?)
1. esd protection on usb/hdmi/ethernet
2. power coupling + bypass cap at each device/output (gpio/usb/hdmi/cm4)
3. power coupling caps at the power inputs (+5V, +3,3V, +12V)
4. power coupling on the 1,8V and 3,3V voltage rails of the CM4 to filter out noise
how do i go about calculating power coupling caps? can i just use some high value like 680uF (+0,1uF for bypass caps?)
or should i do it more conventional? 0,1uF + 10uF at devices and some more capacitance at the power inputs?
0,1uF OR 0,1uF + 10uF seems pretty standard
it might not matter much but a overvoltage protection at the power inputs might be useful too...
tho i kinda need some design tips, since its my first pcb, if anyone created a SBC layout
---
i will post the following days a schematic from EasyEDA, how it looks so far
i switched the PCIE x1 port against a m.2 m-key slot, it makes for a more "tidy" setup with some m.2 usb hubs like this one:
https://de.aliexpress.com/item/1005005759489134.html
the m.2 slot also doesnt need 12V, the usb hub need just additional 5V
and there is still the option to use this:
https://de.aliexpress.com/item/1005005101491558.html?
which needs additional 12V again
0,1uF OR 0,1uF + 10uF seems pretty standard
it might not matter much but a overvoltage protection at the power inputs might be useful too...
tho i kinda need some design tips, since its my first pcb, if anyone created a SBC layout
---
i will post the following days a schematic from EasyEDA, how it looks so far
i switched the PCIE x1 port against a m.2 m-key slot, it makes for a more "tidy" setup with some m.2 usb hubs like this one:
https://de.aliexpress.com/item/1005005759489134.html
the m.2 slot also doesnt need 12V, the usb hub need just additional 5V
and there is still the option to use this:
https://de.aliexpress.com/item/1005005101491558.html?
which needs additional 12V again
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