General XTAG2 questions w.r.t. DJ kit

Technical discussions related to any XMOS development kit or reference design. Eg XK-1A, sliceKIT, etc.
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jjlm98
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General XTAG2 questions w.r.t. DJ kit

Post by jjlm98 »

Hi all - just a few quick questions about the XTAG2 programmer as it pertains to the DJ kit:

1) I'm replicating the DJ kit on my own board and have added an XSYS header in the same fashion as the reference design, in order to accommodate an XTAG2 programmer. The XTAG2 hardware guide shows UART TX and RX signals that are not used in the DJ reference design. Another block on my board happens to have a UART - can I use the UART exposed through the XTAG2 for my own purposes (for example, implementing a command-line interface with a terminal emulator)?

2) Can I assume all signals along the XTAG2 interface are 3.3-V I/O such that they may safely interface to the XS1-U8A (VDDIO = 3.3 V)? Sans any level translation within the DJ kit, I'm left to assume so. A scope trace of the XTAG2 outputs appears to suggest so to, just looking for confirmation from the experts.

3) Section M.3 of the XS1-U8A data sheet suggests connecting X0D16-19 for the debug signals of the XSYS header. However, the DJ kit schematic appears to connect X0D64-67. What is the reason for deviating from the data sheet suggestion? Is this configurable such that it does not matter?

Thanks in advance.


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Folknology
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Post by Folknology »

1) I believe you can use the Rx/Tx pins on the Xtag2, however unlike the original xtag these do not appear on your OS as a virtual com port (Xtag used a 2 chan FTDI chip one of which was dedicated to vcom like operation). The io of the xtag2 passes through the Xrun command or eclipse, more recently you have been able to redirect io through the xscope which may be a useful alternative within the Xmos code, although such serial IO is rather slow IMHO.

2) Yes AFAIK

3) These pins carry an Xmos 2bit link (4 pins) and are used for xscope, you can use either of them and specify which in your xn file.

regards
Al
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jjlm98
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Post by jjlm98 »

Al - thanks so much for your timely and thorough response.
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