Author Topic: TE0745 JTAG Voltage  (Read 211 times)

th-oc

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TE0745 JTAG Voltage
« on: March 15, 2021, 09:26:25 PM »
Hi,

What voltage should be used for the JTAG when designing a TE0745 carrier? looking at the TE0745 schematic the CPLD bank that connects to the JTAG lines is powered from 3.3V, but on the TEB0745 Carrier schematic, 1.8V seems to be supplied to the TE0790 programmer.

Thanks

JH

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Re: TE0745 JTAG Voltage
« Reply #1 on: March 16, 2021, 07:08:32 AM »
Hi,
JTAG voltage depends on "VCCIO_0" default it's connected to  PL_1.8V --> see schematic page 7

PL_1.8V is available on B2B See schematics page 5.    So use this PL_1.8V voltage for  JTAG VREF

br
John

th-oc

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Re: TE0745 JTAG Voltage
« Reply #2 on: March 16, 2021, 11:02:39 AM »
Hi John,

The JTAG interface to the ZYNQ is 1.8V but I understand it passes through the CPLD U2 to reach the ZYNQ on page 2. It seems like the CPLD bank that is exposed to the B2B connector is powered permanently from 3.3V.
https://shop.trenz-electronic.de/trenzdownloads/Trenz_Electronic/Modules_and_Module_Carriers/5.2x7.6/TE0745/REV02/Documents/SCH-TE0745-02-30-1I.PDF
Could you clarify?

Thanks

JH

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Re: TE0745 JTAG Voltage
« Reply #3 on: March 16, 2021, 11:45:26 AM »
Hi,
sorry my mistake.
You are right, it goes through the CPLD. I've overseen this this morning.

JTAG B2B to CPLD is 3.3V (PS_3.3V) and CPLD to SoC is 1.8V (VIO_0 --> PL_1.8V). --> schematic page 2 like you has also checked.
So CPLD is like a levelshifter. Use PS_3.3V for JTAG VREF.

br
John


th-oc

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Re: TE0745 JTAG Voltage
« Reply #4 on: March 16, 2021, 11:58:42 AM »
Okay thanks for confirming that. However on the TEB0745 carrier schematic it seems like the TE0790 JTAG module is supplied with a 1.8V reference voltage, which seems at odds with the CPLD setup on the TE0745. If I use a 3.3V reference will this mean the UART lines from the TE0790 will also be 3.3V which  could cause damage to the MIO pins on the Zynq which are 1.8V on the TE0745?

https://shop.trenz-electronic.de/trenzdownloads/Trenz_Electronic/Modules_and_Module_Carriers/5.2x7.6/5.2x7.6_Carriers/TEB0745/REV01/Documents/SCH-TEB0745-01.PDF

Thanks

JH

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Re: TE0745 JTAG Voltage
« Reply #5 on: March 16, 2021, 01:09:09 PM »
Hi,
you has TEB0745-01 schematic. On REF01 this was a bug which was fixed with REV02

Please use TEB0745-02 sources:
https://shop.trenz-electronic.de/en/Download/?path=Trenz_Electronic/Modules_and_Module_Carriers/5.2x7.6/5.2x7.6_Carriers/TEB0745/REV02/Documents

it use 3.3V (schematic page 26). which is the same link PS_3.3V (carrier schematic page 3 --> J2 connector compare this with J2 of the module)

br
John

th-oc

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Re: TE0745 JTAG Voltage
« Reply #6 on: March 16, 2021, 01:20:51 PM »
Thank you, looking at this schematic makes much more sense.

JH

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Re: TE0745 JTAG Voltage
« Reply #7 on: March 17, 2021, 07:33:17 AM »
Hi,
you can also use the altium project for this carrier:
https://shop.trenz-electronic.de/en/Download/?path=Trenz_Electronic/Modules_and_Module_Carriers/5.2x7.6/5.2x7.6_Carriers/TEB0745/REV02/HW_Design

altium viewer is free available (only registration), in case you use a other CAD program for your PCB design.

br
John