J-link can't find CC2650

Anthony Vavreshchuk

Other Parts Discussed in Thread: CC2650

Hello,

I have a custom made board (based on CC2650 Sensor tag schematic) and I am using SEGGER J-link.

The problem is that J-link doesn't see cc2650 using SWD. I've connected VDD, GND, RESET, TMS and TCK pins. J-link indicates that RESET is always active - 1.3V (powering with 3V).

I'm adding two screenshots: first with adding " -device cc2650f128" as agument and second one without.

over 10 years ago

0 pixbroker over 10 years ago

Genius 5820 points

Try to connect the other 2 JTAG pins as well and try without SWD. Take a look at the CC_DEVPACK_DEBUG for reference of JTAG connection to the sensor tag.

0 svendbt over 10 years ago

TI__Mastermind 29650 points

In addition to pixbroker's suggestion I would double check your connections. If 1.3V is correct it sounds a lot like either the pin is connected to DCOUPL (1.28V or there are one pull-up and one pull-down drawing in opposite directions.

Regards;
Svend

0 Anthony Vavreshchuk over 10 years ago in reply to pixbroker

Prodigy 170 points

Thank you for a reply

I connected the other 2 pins (TDI & TDO) and J-link's output is still the same.

It's RESET pin that disturbs me. J-link signalises about constant active-low RESET: 1.4V (with 2.2V on VDD). Is there any way cc2650 could constantly reset itself?

0 Anthony Vavreshchuk over 10 years ago in reply to svendbt

Prodigy 170 points

Thanks for your reply
On DCOUPL pin it's 0V and it goes through 1uF capacitor to GND.
RESET is pulled up through 100kOhm (also it has 0.1uF capacitor to GND).

0 svendbt over 10 years ago in reply to Anthony Vavreshchuk

TI__Mastermind 29650 points

If you see VDDR different from 1.7V and DCOUPL different from 1.28V (such as 0) then the device probably has not started up yet. Have you powered the device properly? What is the current draw on the board? Does the regulated voltages look OK when the debugger is not connected?

Svend

0 Anthony Vavreshchuk over 10 years ago in reply to svendbt

Prodigy 170 points

Thanks to you, I've checked and fixed one power circuit issue (VDDR was connected to another part of circuit with 1.8V source). The other connections look OK.

After that I have: 3V on VDDS; 0.52V on VDDR; 0.73V on RESET and 0V on DCOUPL. All of this is measured without debugger. Current draw is less than 10mA.

0 Anthony Vavreshchuk over 10 years ago

Prodigy 170 points

Now I'm trying the External Regulator Mode, with 1.8 V supply only. And I googled that 49th pin (the center of chip) shouldn't be connected to ground - is that right? The Technical Reference Manual doesn't mention such, but with that connection resistance between VDD and VSS is about 500kOhm.

0 svendbt over 10 years ago in reply to Anthony Vavreshchuk

TI__Mastermind 29650 points

The center pad of the chip (EGP) must be grounded for devices where this is the only ground connection. These are the 7x7 and 5x5mm devices.
Pins and connections are described in the datasheet: www.ti.com/.../cc2650.pdf

Regards,
Svend