Watchdog on startKIT processor

All technical discussions and projects around startKIT
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Watchdog on startKIT processor

Postby aclassifier » Tue Apr 04, 2017 6:02 pm

XS1-U16A-128-FB217 Datasheet [1] tells about the watchdog timer. XS1-L8A-64-TQ48 Datasheet [2] does not. Both are referenced in the startKIT manual [3]. So, is there a watchdog timer here or isn't it?

Anyhow, this code compiles and returns 1 (ACK) but I see no restart and read no value back. Code at start-up only, so I don't trigger the watchdog, so it should time out and restart. I have tried not kicking the watchdog, just enable it. Still does not restart the processor.

What did I miss?

Code: Select all

int node_config_reg_return; // I have cheched the returns and they are all ACK but I have left them out here
unsigned num_1khz_cycles = 1100;

write_node_config_reg (tile[0], 0xD7, 0); // Enable watchdog. Disable, use 0x0D15AB1E
write_node_config_reg (tile[0], 0xD6,        num_1khz_cycles);                    // Kick watchdog 1 of 2
write_node_config_reg (tile[0], 0xD6, (compl num_1khz_cycles) bitand 0x0000FFFF); // Kick watchdog 2 of 2

[1] ... .10%29.pdf
[2] ... 1.3%29.pdf
[3] ... 1.3%29.pdf
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Postby peter » Wed Apr 05, 2017 8:07 am

The U series devices (XS1-U16A-128-FB217) have an analog node (page 12 of the U16A datasheet). This analog node is where the watchdog timer was located. The startKIT is using a U16A device to create both an XTAG debugger and an equivalent L8A device. The XTAG debugger is using the analog node because it provides the USB PHY and as a result there is no watchdog timer available for the L8A device - the programmable part of the startKIT.

Does that make it clear?
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Postby aclassifier » Wed Apr 05, 2017 10:12 am

Thanks very much for your response!-)

And, well.. I have been trying to find out of the flora of XMOS processors in a list [4] with help from [5]. I must update it a little now, with the not watchdog info.

I have been watching page 12 of U16A and had guessed, since [3] referred to it that it was the top (left (core) and right (analog node)) parts that were in the startKIT processor. I am sorry, I may have mislead you about [2] that refers to L8A, that's not what the startKIT manual states. I don't know how I came across [2]. The startKIT manual states A8A as the other document/processor to refer to [6]. It doesn't have watchdog either. Now, if I swap "L8A" with "A8A" in your reply above, is your answer still valid? (Or did I mess up that one, too?)

Why didn't XMOS just make a two-page document with the final architecture of the 8A6C5DEV (printed on it) on the startKIT? Or have they?

So now, what else of page 12 of the U16A document is not on the 8A6C5DEV? The ADC as described on page 12 probably is a different one on the 8A6C5DEV, since it's using the analog node for the XTAG interface? (I live with the ADC noise matter [7]) Is it correct to say forget the analog node of page 12 and watchdog and ADC and think XTAG and USB? But the brownout is still there, I assume.

If I were on the xTIMEcomposer team would have found some scheme to disallow any stupid coder like me to compile this code. It even returned a 1, and it did generate code. And, no, I couldn't find any words to let me down either. But now I can refer to this thread.

[4] ... processors
[5] viewtopic.php?f=26&t=4959
[6] ... 1.4%29.pdf
[7] ... ed_by_xmos

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