Quick review ?

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SpacedCowboy
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Quick review ?

Postby SpacedCowboy » Fri Aug 23, 2013 9:25 pm

If someone could take a quick look over the schematics below, I'd much appreciate it. It's the first time I've laid out an XMOS chip on a board, so before I send it off for manufacture, it'd be good to know it's at least likely to work :)

Cheers
Simon.
Attachments
xmos-sch1.png
xmos schematic
(141.41 KiB) Not downloaded yet
xmos-sch1.png
xmos schematic
(141.41 KiB) Not downloaded yet
xmos-sch2.png
power schematic
(43.06 KiB) Not downloaded yet
xmos-sch2.png
power schematic
(43.06 KiB) Not downloaded yet
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Bianco
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Postby Bianco » Sat Aug 24, 2013 5:21 pm

- C28 and C31 should be connected to the output of the inductor and ground, not 'behind' C27 and C30.
- C2 and R3 should be swapped, i.e. the resistor connects to 3V3 and the capacitor to ground. R3 should have a value of 4R7, not 4K7.
- There is no proper reset signal generated on power-up, the XMOS chip does not have a power-on-reset circuit build in.
- A pull-up resistor on the chip select line of the boot flash is recommended.
- You can connect the MODE2 and MODE3 pins of the XMOS chip to the TRST_N pin of the XTAG2 connector and you can connect TRST_N of the XMOS chip to the RST_N of the XMOS chip. In this way the debugger can restart the XMOS chip in JTAG boot.
- Point of readability improvement: It is unclear which XMOS part you use. You use a multi-part schematic symbol, it is unclear which sub-parts belong to each other.
The sub-parts seem like an L1 in a TQFP-128 package, but what is that part in the lower right corner? a second XMOS chip?
- Point of readability improvement: oscillator frequency is not specified in the schematic.
- I assume you have other devices that are not on these two images that do use 5V

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