• State TI Thinks Resolved
  • Locked Locked
  • Replies 11 replies
  • Answers 1 answer
  • Subscribers 54 subscribers
  • Views 811 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CC2640R2F: Debug, Program and Antenna connection

Ifthekhar Ahammad
Prodigy 225 points
Part Number: CC2640R2F


Hello,

I am a bit curious regarding the JTAG communication of the CC2640R2F IC and the antenna design. I would appreciate it greatly if you can give me the solution to some of my questions.

I am using the "CC2640R2F Launchpad" design as a reference. In the Launchpad I have the connector "P7" and "P5" as well as the "P4". If all the jumpers on the "P4" are connected then I can directly use the onboard Micro USB connector to upload the program as well as can perform the debug if necessary. Similarly, if I remove all the jumpers from "P4" and just connect the "P7" and "P5" connector of the Launchpad through the Tag cable, I can perform the same. My question is that what is the difference between these two connections (P7 and P4)?

From the schematic, I can see that "P4" have a few more extra connection than the "P7". What is the purpose of those extra connections?

I am planning to use the "TC2050-IDC-NL" (reference image J1) PCB trace connection to program and debug my device using this cable and I want to use the connector "P7" of the "CC2640R2F Launchpad" to program my device. Would I lose any feature if I don't put a connector on my device to connect with the "P4" connector of the LaunchPad and only put the "TC2050-IDC-NL" PCB trace connection?


I also have a few questions regarding the antenna design. I have very little understanding of antenna design, so I tried to follow the reference "CC2640R2F Launchpad" antenna design. I have included a small section of my design (included image). It's in no way the actual placement of all the components, I just have put the components to get a better understanding of the design and the dimensions of the PCB. Anyway, I am mostly interested to check the performance of the PCB trace antenna and chip antenna but I also have included the UFL antenna connector. Based on the performance, later on, I'll only keep one of them. Most probably the chip antenna. Only one of them will be active at a time, I used the DNM capacitor footprint to connect only one of them at a time. My concern is that as I am keeping all of them, how should I lay them out?

I have seen guidelines for single antenna-based designs but could not find anything for a design that includes multiple antennas in a design. Should I use Ground stretching to keep them separate? Is there an antenna design guide that I can use as a reference to lay them out?

Secondly, from the image, you can see that the PCB antenna is not connected to the antenna's passive components through a straight PCB trace. As well as the chip antenna is also placed in a right angle manner with respect to the PCB trace connection. Will that hamper the antenna efficiency? Will it be alright if I put the chip antenna very close to the long arm of the PCB trace antenna?

For antenna design, efficiency-wise, it looks like the PCB trace antenna has the highest efficiency. As I have very little understanding of antenna design, I am not sure how the power consumption of the device is dependent on the Antenna design. I can understand that if the antenna does not have good efficiency and the Bluetooth device is actually far away from the Mobile phone then the device may try to transmit for a longer period of time to get a proper connection. But if the device is only 4 to 5 meters away from the mobile phone does the antenna size matter?

In that case how bigger power loss are we talking about if I use the chip antenna instead of the PCB antenna?

I want to make the device as small as possible, do you have any recommendations for an even smaller size chip antenna that will have higher efficiency?

 

Thank you very much for your time and consideration. Please feel free to contact me if you need any further information.

 

Best Wishes,
Ifthekhar

  • 0
    TI__Guru** 101490 points

    Hi Ifthekhar,

    Due to Thanksgiving holiday, a large part of our teams is out of the office.

    Please expect an answer next week.

    Thank you for your patience.

    Best regards,

  • 0 in reply to Clément
    Prodigy 225 points

    Hello Clément,

    Thank you for letting me know and Happy Thanksgiving Relaxed.

    Best Wishes,

    Ifthekhar

  • 0
    TI__Guru**** 219597 points

    Hi Ifthekhar,

    SIMPLELINK-2-4GHZ-DESIGN-REVIEWS would also be a great resource to utilize.

    Regards,
    Ryan

  • 0 in reply to Ryan Brown1
    TI__Genius 15590 points

    Hi Ifthekhar,

    Ifthekhar Ahammad said:
    My question is that what is the difference between these two connections (P7 and P4)?

    P7 is a header that utilizes jumpers to connect the debug signals from the onboard XDS110 to the device, and P4 is a header that serves the same purpose but if you wanted to use the onboard XDS110 as an external debugger. If you were using P4, you would remove the jumpers from P7.

    Ifthekhar Ahammad said:
    From the schematic, I can see that "P4" have a few more extra connection than the "P7". What is the purpose of those extra connections?

    SWO and UART. These aren't necessary for programming the device, just nice to have for debugging software

    Ifthekhar Ahammad said:
    Would I lose any feature if I don't put a connector on my device to connect with the "P4" connector of the LaunchPad and only put the "TC2050-IDC-NL" PCB trace connection?

    Not necessarily. If you copy the pin assignments like P5 then it would be the same functionality

    As for your antenna questions, I will reach out to our antenna expert for comment.

    Thanks,

    Alexis

  • 0 in reply to Alexis Crandall20
    TI__Mastermind 33830 points

    Hi,

    Even if the communication distance is just a few meters, it's good practice to keep the antenna efficiency as high as possible so that the conducted output power can be reduced instead.

    I would not use the chip antenna and the PCB integrated antenna as shown above. I would remove the chip antenna completely and flip the pcb antenna horizontally. 

    Ideal to have a pi-network for the antenna matching for the pcb antenna. Even if you would use a chip antenna, a pi-network should still be recommended from the antenna chip vendor.

    If you reduce the size of the antenna or the board, the antenna efficiency would drop especially if the GND plane size is reduced less than a quarterwave (3.1 cm). Keep as much GND clearance to pcb antenna as possible. I would stop the GND fill area at the red line in the figure.

  • 0 in reply to RGW
    Prodigy 225 points

    Hello ,

    Thank you very much for your reply. I already have changed the design a little bit. I am attaching an image of the new design as well. Do you think that I should flip the PCB antenna here as well? This time I tried to maintain the Pi-model based on the "SIMPLELINK-2-4GHZ-DESIGN-REVIEWS" document.

    Right now the size of my PCB board is quite big for the prototyping purpose but the final device needs to be very small. At that time I may not be able to use the PCB trace antenna. That's why I want to see the performance of the chip antenna as well. So in your opinion, as I want to keep both of them, Where and how should I put both the PCB trace antenna and the chip antenna in my design?

    I'll prepare a couple of boards, so on one board, only the PCB trace antenna will be active and I will not solder the chip antenna on that one, and on the other one only the chip antenna will be connected.

    The distance between points "A" and "B" is 1.52mm, C to D 4.01 mm, E to F 8.18mm, G to H 2.24mm. Should I put an isolation slot in between A to B? Based on the launchpad reference design, I know that I need to keep the G and H points very close to each other so that that part of the antenna can be connected to the GND plane. Right now I have left it like this to show how much space I can dedicate for the PCB trace antenna in this board, I think I also need to stay a certain distance away from the board's edge, so when I am sure that my antenna placement is correct, I'll bring the G point close to the H point, including the whole antenna.  

    Lastly, is there any reference design document from TI on how and where to place the Chip antenna for achieving the best performance?

    Again thanks a lot for all the helpful suggestions.

    Best Wishes,
    Ifthekhar

  • 0 in reply to Alexis Crandall20
    Prodigy 225 points

    Hello Alexis,

    Thank you very much for all the helpful information.

    Best Wishes,
    Ifthekhar 

  • 0 in reply to Ryan Brown1
    Prodigy 225 points

    Hi Ryan,

    Thanks for the reference document. I was able to make quite a few changes based on it.

    Best Wishes,
    Ifthekhar

  • 0 in reply to Ifthekhar Ahammad
    TI__Mastermind 33830 points

    Hi,

    I would flip the antenna in this design as well.

  • 0 in reply to RGW
    Prodigy 225 points

    Thanks.

    Ifthekhar Ahammad said:
    Where and how should I put both the PCB trace antenna and the chip antenna in my design?

    Do you have any suggestions regarding the placement of the chip antenna as well?

  • 0 in reply to Ifthekhar Ahammad
    TI__Mastermind 33830 points

    I would not use the chip antenna. There's a large risk that using both antennas will degrade the performance. The inverted F-antenna design has been used on many projects and is a reliable solution.