I'm trying to build and load a linux kernel onto a R7S721001 processor and I'm using the GR-Peach as my evaluation board. However, connecting the JTAG interface to the J-Link produces a "TDO is constant high." error.
I thought I'd found the issue when I discovered that the nRZRST pin (pin 10) was not connected. The schematic I found for the board shows a R29 resistor but marks it as "not mount", so I looked for the empty spot, checked for a resistance with pin 10, and then shorted the connection with some solder. However, the J-Link still produces the "TDO is constant high" error.
Here's the Output from the JLinkExe Commander:
SEGGER J-Link Commander V6.54a (Compiled Oct 31 2019 17:38:48)DLL version V6.54a, compiled Oct 31 2019 17:38:34
Connecting to J-Link via USB...O.K.Firmware: J-Link EDU Mini V1 compiled Oct 22 2019 16:28:45Hardware version: V1.00S/N: 801012842License(s): FlashBP, GDBVTref=3.282V
Type "connect" to establish a target connection, '?' for helpJ-Link>connectPlease specify device / core. <Default>: R7S721001Type '?' for selection dialogDevice>Please specify target interface: J) JTAG (Default) S) SWD T) cJTAGTIF>Device position in JTAG chain (IRPre,DRPre) <Default>: -1,-1 => Auto-detectJTAGConf>Specify target interface speed [kHz]. <Default>: 4000 kHzSpeed>Device "R7S721001" selected.
Connecting to target via JTAGCould not measure total IR len. TDO is constant high.Could not measure total IR len. TDO is constant high.Could not measure total IR len. TDO is constant high.Could not measure total IR len. TDO is constant high.Cannot connect to target.
Incase others come here with "J-Link cannot connect" issues, note that Segger have a Wiki page on resolving connection issues:
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