JTAG Scan Chain Length
From Texas Instruments Embedded Processors Wiki
JTAG Scan Chain Lengths for processors:
| Core/Controller | IR length | IR Bypass | DR Length | DR Bypass |
| 6201/6701 | 8 bits | |||
| 621x/671x | 46 bits | |||
| 64x+ | 38 bits | |||
| 672x | ||||
| 674x | 38 bits | |||
| 54x | ||||
| 55x | 38 bits | |||
| 55x+ | 38 bits | |||
| ARM7 | 4 bits | |||
| ARM9 | 4 bits | |||
| ARM11 | ||||
| ARM Cortex M3 | ||||
| ARM Cortex R4 | ||||
| ARM Cortex A8 | ||||
| ARM Cortex A9 | ||||
| ICEPick-B | ||||
| ICEPick-C |
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Comments on JTAG Scan Chain Length
We are testing a DSP board with 4 TMS320C6455 1GHz DSPs. The four DSPs are connected to JTAG chain. We have Spectrum Digital XDS510SUSB emulator cable. The SDConfig program reports no fault, but the JTAG chain length is reported 24 four devices. The 24 probably a wrong number, because one DSP IR Length is 38 bit.
The Code Composer Studio cannot connect to the DSPs.
The TCK signal has been check by scope, seems to be all right.
The board was designed according to the current chip errata.
What could be the problem?
--Koller 12:42, 9 February 2010 (CST)