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Effect of poor antenna design while using CC3200.

Kumar Nishant
Prodigy 110 points
Other Parts Discussed in Thread: UNIFLASH, CC3200MOD, ENERGIA, CC2538, CC3200

I have designed my own PCB using CC3200MOD. I uploaded latest firmware using UNIflash and programmed using Energia IDE. I ran some simple codes which didn't involve WiFi functionalities successfully. But as soon as I run any code which involves the use of WiFi, it restarts and this process goes on in a loop. I have designed almost entire PCB using TI's reference design (for CC3200MOD development board) except the antenna part in which I did small changes to fit my PCB shape and size limitations.

To be more specific, the clearance between ground pour and antenna trace is 18mil in MOD datasheet and 10mil in my design. Though i checked that in CC3200MOD laucnhpad the clearance is just 6mil. I kept the trace width same but the length is bit shorter.

My question is:

1. Can it be an antenna issue? What is the worse that can happen due to improper antenna design?

2. Can this be a firmware issue? The same firmware which I used in my design is running properly in Launchpad.

My guess is that improper antenna design should at max lead to poor reception or low range and should not lead to restarting the Chip. Please help.

  • 0
    Prodigy 110 points
    Update 1: Somebody suggested that it may be a power issue. So I provided an external power supply to the chip, but the same problem persists. I measured the voltage on power rail, it was pretty stable between 3.23 to 3.27V and current consumption was between 41-42mA. I measured voltage and current using a digital multimeter, I am not sure if multimeter is fast enough to see voltage drop which might be happening for really small time as the module restarts in loop. But I now guess that power shouldn't be a problem as I the supply has 1A capability @ 5V.
  • 0 in reply to Kumar Nishant
    TI__Genius 11120 points
    A poor antenna design will not cause this problem. This is indicative of poor power supply regulation. This is not a firmware issue either..
  • 0 in reply to Prajay Madhavan
    Prodigy 110 points

    Thanks Prajay for the reply. It is indeed not an antenna problem. 

    To give you some background, my custom PCB contains both WiFi (CC3200) and Zigbee (CC2538) chip on the same PCB. I made 2 custom PCBs. One of them is working after some changes. Lets name the board which is working as B1 and the one not working as B2. I tried the running "out of box" code in B2 but it gets stuck in line portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; (line 372) in function void vPortYield( void ) in port.c file of freeRTOS.

    Here are the things that I did to both of them:

    1. Added some grounding by connecting the ground pin to different points on the ground plane with external copper wire, so they are slightly different on B1 and B2.
    2. Added 300uF decoupling capacitor.
    3. Added jumper between P58 and Vcc for all codes.
    Here are the differences between B1 and B2 that I know of:
    1. The manufacturer for the 3200 MOD seems different (the stickers on the MOD are slightly different).
    2. The grounding was done by connecting the ground pin to different points on the ground plane with external copper wire, so they are slightly different on B1 and B2.
    3. B1 doesn't have the CC2538 (and its supporting components) soldered, while B2 is complete with all the components for 3200 and 2538 soldered.
    I am not able to think of anymore debugging points, please suggest.
  • 0 in reply to Kumar Nishant
    Prodigy 110 points
    Update: The first picture is of the Module used in B2 (not working board) and the second Module is used in B1 (working board).
  • 0 in reply to Kumar Nishant
    TI__Genius 11120 points
    I dont think there is any difference in the module. The sticker is different as we added Telec logo..
    You may want to check the power supply integrity by probing with a scope. Under no circumstances should it dip below 2.1V
  • 0 in reply to Prajay Madhavan
    Prodigy 110 points

    Thanks Prajay. Yes the modules are same.

    I managed to run the second board as well. The reason I was not able to run it earlier was power.The board B2 had CC2538 along with CC3200 and the power was not enough for both. I provided power at the CC2538 Vcc & Ground pins and the board ran smoothly.

    I will now have to do the power supply integrity as you suggested. I will update the progress.