I would like to test the DP83640 we have in external loopback mode for production testing. The device is fully functional i.e. Ethernet functions OK and I can read/write registers via the SMI bus; expected values such as the device and vendor ID are read correctly.Ive setup the device NOT in loopback mode setting both the:
BMCR, 0 = Normal operation
10BTSCR, 1 = 10BT Loopback is disabled
which the PHY status register confirms.
I set the PHYCR 'BIST Start' to 1 and poll on BIST Status to check the bit isn't zero indicating failure.
When complete the top byte of CDCTRL1 is read to retrieve the number of errors.
The problem is that regardless of having the loopback connector (very short wires - RJ45 loopback) plugged in or out, the error count is always zero.
I expect the error count to be 0xFF, is this wrong?
If the device detects no link (as indicated in the status register), is the count supposed to be zero?
Ive tried going through the registers and setting them up and copying any register values on here from other support queries, all produce the same result. e.g.
https://e2e.ti.com/support/interface/ethernet/f/903/t/282512
In this thread, the technician writes that 0x3 should be written before the error count read... it would be helpful if he had mentioned which register?
Could someone provide definitive register configuration to get external loopback test working?
Thanks
