Logger to USB stick running on KL25Z
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Table of Contents
Homepage for kXX_logger(was kl25x_usb_logger)¶
2014Nov12 - Added TSI - only works for kl25z, and fails after 4287seconds¶
Tests sequences for freezing 4287seconds 4287 4287 - Changed to USB write update every two seconds and lasted 4283seconds. Added mbed TSI_sensor - kudos to mbed as it turns out to be complex to do capacitive touch sensing. Kinetis L series Cortex-M0 (kl25z) has simpler capacitive sensing hardware which mbed/TSI_sensor lib uses, but doesn't support Cortex-M4 versions. K20D is older more complex interface. TSS hasn't had an open source support by Freescale in the past however that has changed. Currently I found KDS1.1.1 has a Processor Expert TSSlib that can be imported - but I'm getting a weird compile/include error - and not found any examples of how to make it work.
2014Oct05 - Published simple kl25z_usb_logger¶
Testing: Version (2:f06fbf86887e) has run over 28days starting 2014Sept07, reading a sensor data every seconds and then on the USB stick open file, write record, close file
This is over 2,419,200seconds ( 28days*24hrs*3600seconds) The stick data reflected 2,447,633 seconds, but only had 1,776,366 data records. After 407,650 data records started missing updates - analysis: the file could not be opened and read to the end in the allocated 1 second, and therefore missed the next ADC deadline.
By the end of the test period with 1,776,366 records on the USB Stick, ever read then write was causing it to miss two/three ADC updates - ie taking longer than two seconds.
Analysis: this was an aggressive test, and normally would not be opening, writing, closing every 1 second. However big plus the file mechanism held up and the program continued to operate, with a graceful failure of a missed ADC readings. The output used JSON, which reads nicely but turns out not to be supported by Excel (2014?) I was using.
Conclusion: Overall the USB Mechanisms and file read is stable. However the USB stack used doesn't have an event based management for stick insertion and removal, or OTG power management . This KL25Z has been a very useful test to prove the configuration of clocks for USB Stack is possible and stable. The target processor being looked at is the MK20 and is similar in clocks, but slightly more comprehensive USB OTG Next step is to investigate the full Freescale Kinetis USB OTG Stack with power management on a custom K20 board, using Kinetis Design Studio, and very low power capability.
Example https://github.com/ErichStyger/mcuoneclipse/tree/master/Examples/FRDM-K20D50M/FRDM-K20_MSD_Host http://mcuoneclipse.com/2014/10/25/usb-cdc-with-the-frdm-k64f-finally/#comment-37727 - Commentary on Freescale USB versions