Some confusions regarding XK-1A board

Technical questions regarding the XTC tools and programming with XMOS.
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jagspaul
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Some confusions regarding XK-1A board

Post by jagspaul »

Regarding XK-1A I have some queries as following below.

1) In XK-1A schematic no power on reset chip found. The chip reset pin RST_N is connected to JTAG –IN connector. That means the chip will be reset by XTAG-2.

My question:
After flashing binary when the board is powered on (stand alone) with out XTAG-2 then how power on reset is done properly?

2) In XK-1A board two x-links are used. Link-C connected with JTAG-IN terminal & Link-D is connected with JTAG-OUT terminal. That means when multiple boards are connected via x-link then slave board will be booted through x-link C as it is connected with JTAG-IN terminal.

My question:
As per documentation XMOS L1 chip can boot through x-link B not link C. Then how XK-1A boots over xlink. On another point MODE PIN 3&2 both are connected together and pulled UP. So the boot sequence can be set 0,0 & 1,1. Then in case of multiple board how slave boards boot sequence are set to boot over xlink.

regards
jags


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segher
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Post by segher »

1) The RC network formed by R5 and C22 pulls TRST_N high after some delay.

2) You cannot boot an XK-1A via xlink, not directly that is: you can only directly
boot it from SPI or via JTAG, as you found out. The code you boot that way can
of course listen for a new boot image on whatever xlinks it wants: the limitation
that you can only boot over external link B (or the internal links) is a limitation of
the boot ROM code, not of the hardware.
jagspaul
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Joined: Tue Oct 18, 2011 3:28 pm

Post by jagspaul »

segher,

Thanks for your reply.

1) As reset is done by RC network on XK1A board, then in my new L1 86 pins board, Can I use same RC network for reset instead a reset controller?

2) I put a ticket to XMOS support regarding booting over xlinks of XK-1A board. They are claiming that due to custom boot loader burnt on OTP XK-1A board boots over xlink-C instead link-B (default).

jags
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segher
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Post by segher »

1) Yes. It is much easier to get a proper reset controller working
reliably though.

2) Interesting. How should you set the MODE pins to make this
work? I guess I can peek at the code in OTP, I never knew there
was any :-)
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