• Yasushi SHOJI's avatar
    can: mcba_usb: Fix termination command argument · 1a8e3bd2
    Yasushi SHOJI authored
    Microchip USB Analyzer can activate the internal termination resistors
    by setting the "termination" option ON, or OFF to to deactivate them.
    As I've observed, both with my oscilloscope and captured USB packets
    below, you must send "0" to turn it ON, and "1" to turn it OFF.
    
    From the schematics in the user's guide, I can confirm that you must
    drive the CAN_RES signal LOW "0" to activate the resistors.
    
    Reverse the argument value of usb_msg.termination to fix this.
    
    These are the two commands sequence, ON then OFF.
    
    > No.     Time           Source                Destination           Protocol Length Info
    >       1 0.000000       host                  1.3.1                 USB      46     URB_BULK out
    >
    > Frame 1: 46 bytes on wire (368 bits), 46 bytes captured (368 bits)
    > USB URB
    > Leftover Capture Data: a80000000000000000000000000000000000a8
    >
    > No.     Time           Source                Destination           Protocol Length Info
    >       2 4.372547       host                  1.3.1                 USB      46     URB_BULK out
    >
    > Frame 2: 46 bytes on wire (368 bits), 46 bytes captured (368 bits)
    > USB URB
    > Leftover Capture Data: a80100000000000000000000000000000000a9
    Signed-off-by: default avatarYasushi SHOJI <yashi@spacecubics.com>
    Link: https://lore.kernel.org/all/20221124152504.125994-1-yashi@spacecubics.comSigned-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
    1a8e3bd2
mcba_usb.c 21 KB