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Blinking a LED using CC2541.

Swarika Jain

Intellectual 555 points

Other Parts Discussed in Thread: CC2541, CC-DEBUGGER

I want to run a sample program on CC2541 using IAR Embedded Workbench so that I can be sure that I am able to upload programs on CC2541. I opened SimpleBLEPeripheral in IAR embedded workbench. I added a line "P1_5= 1;" in simplebleperipheral.c and connected an LED through 470ohms on CC2541 chip. I have connected all the supply and ground pins and have also connected oscillators to the CC2541 according to the schematic provided on TI website. I have not yet connected an antenna.

Now, when i burn the program in the chip, it does not produce the desired result. The LED does not turn on or off according to the program.

Can you please help me identify the problem?

over 11 years ago

0 Eirik V over 11 years ago

TI__Guru 56590 points

Hello Swarika,

Start by using the CC2541/43/44/45 Peripherals Software Examples instead. They are must easier to start with and do not use the radio.

0 Swarika Jain over 11 years ago in reply to Eirik V

Intellectual 555 points

Thanks Eirik.

I will try the software examples and will get back soon.

0 Swarika Jain over 11 years ago in reply to Swarika Jain

Intellectual 555 points

Hi Eirik,

Thanks a lot for your advice. The software examples are much easier to start with.

Please help me with the connections of LED.

I have made a breakout board of CC2541 which has oscillators and necessary components. I have kept out pins for general purpose input output.

If I connect an LED in the following manner, will it be correct?

- anode to P1_0

-cathode to one end of 470ohms resistors

-other end of resistor to ground

Is the above connection right?

Please suggest.

Regards,

Swarika

0 Eirik V over 11 years ago in reply to Swarika Jain

TI__Guru 56590 points

Yes,

You are correct, but you must look at the datasheet for the LED you are using to check how much current it requires for the desired brightness. For example if you power the board from 3.3 V now you will most likely have about 5.5 mA of current going through the LED if the LED has a voltage drop of 0.7 V . The resistor can be at either end as it will limit the current through the whole chain.

Current_led = (Supply - LED_Voltage_Drop) / Resistance

0 Swarika Jain over 11 years ago in reply to Eirik V

Intellectual 555 points

Hi Eirik,

I was able to run the program successfully. Thanks a lot.

Now, when I would connect the antenna to CC2541, then will I again have to switch back to SimpleBLEPeripheral or are there any other simpler example programs to test the working of antenna?

0 Eirik V over 11 years ago in reply to Swarika Jain

TI__Guru 56590 points

Hello Swarika,

You can connect the device to SmartRF Studio and enable packet transmission, reception and continues wave (CW). You can also test the proprietary mode packet error rate tester (CC254x Proprietary Mode Packet Error Rate Test (Rev. B))

0 Swarika Jain over 11 years ago in reply to Eirik V

Intellectual 555 points

Eirik,

Okay I will try that. Thank you.

Also,

I ordered balun and antenna of Johanson Technologies as mentioned in the schematic provided by TI. But, they are also SMD components. So, if I make a breakout board for these two chips and connect them through wires to CC2541, will It work?

Thanking you in advance.

Regards,

Swarika Jain

0 Eirik V over 11 years ago in reply to Swarika Jain

TI__Guru 56590 points

Hello Swarika,

No! It could only work on very low frequency devices (far outside the band our devices are designed for).

Design all RF components on the same PCB board and copy our reference design as precisely as possible. Even the smallest change might impact the performance and it requires very expensive RF measurements equipment and knowledge to correct mismatch.

If you copy our design you should have good start :).

0 Swarika Jain over 11 years ago in reply to Eirik V

Intellectual 555 points

Oh okay.

Thank you so much Eirik.

Regards,

Swarika Jain

0 Swarika Jain over 11 years ago in reply to Swarika Jain

Intellectual 555 points

Hi,

I am getting my own PCB manufactured based on the schematic provided by TI.

The link to the schematic is http://www.ti.com/lit/ml/tidr203a/tidr203a.pdf

A few components have been marked as DNM, what exactly do we mean by DNM capacitors?

Also, how important is it to put 0ohm resistors.?

0 Eirik V over 11 years ago in reply to Swarika Jain

TI__Guru 56590 points

Hello Swarika,

DNM is an abbreviation for "Do Not Mount". It means that there should not be mounted any components there during fabrication. Only the footprints for the components are desired to be able to add matching components manually after fabrication. The 0-ohm resistor serves the same purpose. It is only there to have a footprint ready for adding matching components, but because the RF path must be connected a 0-ohm resistor is added to simply connect the two points.

If you copy the layout precisely and use the same PCB type an material you can probably omit the footprints for the three matching components and still achieve close to optimal RF performance.

0 Swarika Jain over 11 years ago in reply to Eirik V

Intellectual 555 points

Hi Eirik,

Thanks a lot.

Regards,

Swarika Jain

0 Swarika Jain over 11 years ago in reply to Swarika Jain

Intellectual 555 points

Hi Eirik,

I have bought the Bluegiga BLE113 module to start developing rf codes.

Please suggest a sample program to start with, if I want my BLE113 to just advertise itself so that I can detect it using an iPhone.

Regards,

Swarika Jain

0 Eirik V over 11 years ago in reply to Swarika Jain

TI__Guru 56590 points

Hello Swarika,

Start by using the SimpleBLEBroadcaster.

0 Swarika Jain over 11 years ago in reply to Eirik V

Intellectual 555 points

Thanks a lot Eirik !

Regards,

Swarika Jain

0 Swarika Jain over 11 years ago in reply to Swarika Jain

Intellectual 555 points

Hi Eirik,

I ordered Bluegiga BLE113.

I made the following connections:

pin 1,2,3,4,5,6,7,18,25,36 to CC debugger's pin 1

pin 8,17 to CC debugger's pin 2,9.

pin 9 to CC debugger's pin 3

pin 10 to CC debugger's pin 4

pin 34 to CC debugger's pin 7

But the light on cc debugger is always red. It doesn't go green.

Please suggest where I am going wrong.

Thanking you in advance,

Swarika Jain

0 Swarika Jain over 11 years ago in reply to Swarika Jain

Intellectual 555 points

Hi Eirik,

My problem is resolved. I have successfully connected BLE113 and it is working now.

I had used SimpleBLEBroadcaster and my iPhone is detecting the chip.

Please suggest, which sample program shall I use now in order to get more familiar with IAR programming of TI CC2541?

Regards,

Swarika Jain

0 Swarika Jain over 11 years ago in reply to Swarika Jain

Intellectual 555 points

Hi Eirik,

I have encountered another problem. Please advise.

The led on CC-Debugger goes orange whenever I connect it to my PC whether the chip is connected or not.

Moreover, my PC doesn't detect the CC-Debugger at all. So, I can not update the firmware using RFflash programmer or Studio because both the softwares show that device is not connected.

Please help.

Regards,

Swarika Jain

0 Eirik V over 11 years ago in reply to Swarika Jain

TI__Guru 56590 points

Hello Swarika,

Your CC-Debugger seems to be bricked. Read the following thread on how to restore it:

http://e2e.ti.com/support/low_power_rf/f/155/t/115507.aspx

0 Swarika Jain over 11 years ago in reply to Eirik V

Intellectual 555 points

Hi Eirik,

I bought a new cc-debugger.

Now, I have created my own schematic for TI breakout board.

Could you please review it for me before I place order for PCB manufacturing?

I have inserted my schematic file here. Please have a look.

0458.TI cc2541 schematic.sch

Thanks a lot.

Swarika Jain

0 Eirik V over 11 years ago in reply to Swarika Jain

TI__Guru 56590 points

Hello Swarika,

It looks good, but you have not connected a debug interface (reset, DD, DC, VDD and GND). How will you program the device? Please also note that if you use a different crystal than our reference design you might have to alter the load capacitor sizes.

Compare you design with an appropriate reference design which can be found on the CC2541 product page. Also make sure to copy the antenna and RF layout precisely from the reference layout to have the best chance of good RF performance.

0 Swarika Jain over 11 years ago in reply to Eirik V

Intellectual 555 points

Hi Eirik,

I thought I will connect the debugger lines separately using jumper wires instead of having a 6-pin male header, but now I think I should add a debug interface as it will become easy to connect the debugger to the board.

And I couldn't find the same crystal at my vendor, that is why I am using a different one. The specifications are same,i.e., 32.768KHz-9pF SMD and 32MHz-10pF SMD.

So, when the value and the capacitance of the crystal is same, do I still need to check the value of load capacitance?

Thanks!

Swarika Jain

0 Eirik V over 11 years ago in reply to Swarika Jain

TI__Guru 56590 points

Hello Swarika,

Then I think your board should work.

In some cases when you end up with a wrong load capacitance the board may still work well, but there can be an offset on the frequency which can be observed on a spectrum analyzer. If you enable a CW signal and look at the set frequency you can see the power peak is lightly off. But as i said i think you are good to go.

0 Swarika Jain over 11 years ago in reply to Eirik V

Intellectual 555 points

Okay thanks Eirik,

Can you help me with one more thing please..

I have connected BLE113,

In simpleBLEPeripheral,

I am sending data through characteristic 3 from my iOS..but I don't understand how to read it in my program.

Please tell me which function reads the data received from iOS and how to process that data.

Thank you.

Regards,

Swarika Jain

0 Eirik V over 11 years ago in reply to Swarika Jain

TI__Guru 56590 points

Hello Swarika,

To be honest, my skills are currently lacking with regards to modifying the BLE stack on our devices. I suggest you re-post this question in a new thread in this same forum to make it visible for more experts that can aid you.