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i.MX7D Boundary Scan

Question asked by ericschumann on May 9, 2017
Latest reply on May 15, 2017 by Yuri Muhin

We are trying to get boundary scan to work with Cascon on our phyCORE-i.MX7D SOM. According to the Hardware Development Guide, Table 8:

“5. If boundary scan test (BSDL) will be used, the following supplies must be powered: PCIE_VP, PCIE_VPH, PCIE_VPTX. The boundary scan test scan chain runs through the PCIe PHY. If the PCIe PHY supplies are not powered, the scan chain will not function.”


See the corresponding connections in our schematic below:


For some reason, our scan chain is having issues. We are following the compliance pattern detailed in the hardware development guide (setting JTAG_MOD pin high, releasing POR_B) and have also tested with and without a PCIe device connected in u-boot and Linux, but in all cases the test byte that we shift into TDI is not read out of TDO correctly.


We can turn on the VDDD_1V0_CAP rail by doing a register write in u-boot to 0x30360210, but we have not found a way to turn on VDDA_PHY_1P8 without booting into Linux with a PCIe device connected. Do you know if there's a way to do this?


Do you have any idea what might be going wrong with our scan chain?