Loading SPI_CLK is no good
Posted: Thu Sep 14, 2017 2:10 pm
I am testing an xCORE-200 eXplorerKIT with a WiFI sliceCARD. The full background is described in a blog note [1]. The main problem here goes like this:
If I connect the SPI_CLK output pin to my BitScope USB scope I get a crash when I run in xTIMEcomposer. That goes even if I use a USB isolator. The scope has internal impedance of 1M||50pF. The crash I get looks like this:
This is 100% repeatable. If I connect the scope when it’s started OK then all is fine. // Commented text is mine.
But the elegant message from xrun is more than I understand. How can the program counter become illegal? What's going on?
[1] http://www.teigfam.net/oyvind/home/tech ... otes-wifi/ (Disclaimer: no ads, no money, no gifts, just hobby!) You will also find this XCore text in that blog note, and I will link this up.
If I connect the SPI_CLK output pin to my BitScope USB scope I get a crash when I run in xTIMEcomposer. That goes even if I use a USB isolator. The scope has internal impedance of 1M||50pF. The crash I get looks like this:
Code: Select all
[ 555 ms] **WELCOME TO THE SIMPLE WEBSERVER DEMO**
[ 606 ms] Switching on Wi-Fi module....
[ 657 ms] init
[ 1761 ms] WriteN 1 10 // In wifi_tiwisl_spi_first_write
[ 2416 ms] read2 1 ff.ff // After last spi_master_in_buffer in wifi_tiwisl_spi_read
// in file wifi_tiwisl_spi.xc in module module_wifi_tiwisl
xrun: Program received signal ET_ILLEGAL_PC, Illegal program counter.
[Switching to tile[0] core[1]]
0xffffffff in ?? ()
- If connect a 1M||47pF between SPI_CLK and GND then it hangs after the “init” text. Repeatable
- If connect a 1M||47pF between SPI_CLK and 3V3 then it hangs after the “WriteN 1 10” text. Repeatable
- If I connect any of these when it’s started OK, it stops. I even see it stop during startup with just the 20 cm wire hanging on SPI_CLK
But the elegant message from xrun is more than I understand. How can the program counter become illegal? What's going on?
[1] http://www.teigfam.net/oyvind/home/tech ... otes-wifi/ (Disclaimer: no ads, no money, no gifts, just hobby!) You will also find this XCore text in that blog note, and I will link this up.