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cc2640 standalone circuit

Enrique Ugarte
Intellectual 320 points
Other Parts Discussed in Thread: CC2640, CC2650STK, TPS62730, TPS62740

Hello everyone, I'm building a standalone prototype with the CC2640 and I've seen the datasheets in the ti.com web but I'm a bit confused, I don't know wich schematic use. 

The application I'm building is about a push button: when you press down the push, a signal with data will be sent to a smartphone and a LED will turn on in the board, when you release the push, an other signal with data will be sent to the smartphone and a LED will turn off in the board. This application is very simple, so, if anyone can tellme which schematic I can use I will appreciate very much.

Thanks

  • 0
    TI__Guru** 106705 points

    Hi Enrique,

    The basic reference designs to follow would be the CC2650EM-7ID / -5XD / 4XS. The difference between them is that they use different package sizes (7x7 mm, 5x5 mm and 4x4 mm) and that they all show different RF front-ends you can use. The RF front-ends are not locked to the package sizes, you can mix them as you wish.

    The simplest option in terms of component count and design complexity is the single ended output option. If you do not have any experience with RF design I would recommend to use this.

    Based on your description it seems like you do not need a lot of IOs, so in that case you can use the 4x4 package. The only thing to keep in mind is that the 4x4 has 0.4 mm pin spacing so if you are hand assembling prototypes the 5x5 with 0.5 mm pin spacing might be a better option.

    Follow the reference design layout closely, and you should also take a look at the design tips found in the HW section on the BLE wiki: www.ti.com/ble-wiki.

    Cheers,
    Fredrik

  • 0
    TI__Guru** 105180 points
    Hi Enrique,

    The best example would be a SensorTag 2.0 (CC2650STK). There is an example with keys pressed and notification sent to the phone. Although the Sensor Tag contains more sensors than what you require, you should be able to use this as a foundation for your learning.

    You can find more details on the Sensor Tag 2.0: www.ti.com/.../cc2650stk

    Best wishes
  • 0 in reply to Fredrik K
    Intellectual 320 points
    Thank you very much Fredrik, this has being very helpfull!

    I will consider this for my design and I believe I will use the 4x4. Is there any example code to accomplish my goal described above?
    Which development tools do you recommend me to start?

    Thanks again.
  • 0 in reply to JXS
    Intellectual 320 points
    Thanks JSX!

    I will start with the SensorTag for practice and start coding.

    Again, thanks.
    Best regards,
  • 0 in reply to Enrique Ugarte
    TI__Guru** 105180 points
    Also, please review the FAQ thread at the top of the forum, it will help you get started and point you to the necessary documents / wikis.

    Best wishes
  • 0 in reply to Fredrik K
    Intellectual 320 points
    Hello again Fredrik,

    I'm having some troubles with my development and I have some questions I hope you can help me.
    I'm using the CC2650EM-4XS schematic as reference to build my PCB for my CC2640 stand alone project, I'm going to power my PCB with a CR2032 Battery using the TPS62730 DCDC Regulator, so:
    1.- Do I have to wire the VDDR pins (28, 32) and the DCDC_SW pin (18)? Or can I leave them without connected?
    2.- Is it OK for me to use the TPS62730 DCDC Regulator to power the PCB?
    3.- In the CC2650EM-4XS schematic what does VDD_EB mean?
    4.- Which is the Debug/Flash connector? EM Connector 1 or 2?

    Is there any schematic example running with CR2032 battery?

    Thanks and best regards,
  • 0 in reply to Enrique Ugarte
    TI__Guru** 106705 points

    Hi Enrique,

    For external regulator you should follow the CC2650EM-4XS-Ext_Reg reference design found here: www.ti.com/.../swrc301

    I would highly recommend to use the TPS62740 instead of the TPS62730. I also recommend that you read through the last part of chapter 1 in the technical reference manual. Basically the TPS62740 will output 1.8 V and you must configure the CC2640 for 1.8V operation. In this mode VDDS_DCDC and DCDC_SW are connected to ground and VDDS and VDDR pins are all connected to the 1.8V rail. You must also configure the appropriate fields in ccfg.c.

    The EM boards are designed to plug into the SmartRF06 Evaluation Board and thus does not have dedicated debug header. Take a look at the HW design guides on the BLE wiki for more details ti.com/ble-wiki.


    Cheers,
    Fredrik

  • 0 in reply to Fredrik K
    Intellectual 320 points

    Hello Fredrik,

    Thanks for all the info, it has being very helpful, I finished my design with the data you gave me but I have one last question:

    I want to be able to debug/flash my PCB with the JTAG and I wonder if I make the connections between the CC2640 and the JTAG like this I will be able to do it:

    Pin 2 Conn JTAG to CC2640 pin 13

    Pin 4 Conn JTAG to CC2640 pin 14

    Pin 6 Conn JTAG to CC2640 pin 15

    Pin 8 Conn JTAG to CC2640 pin 16

    Pin 10 Conn JTAG to CC2640 pin 21

    Pin 1 Conn JTAG to VDD

    Pin 3 Conn JTAG to GND

    Pin 5 Conn JTAG to GND

    Pin 7 Conn JTAG (not conected)

    Pin 9 Conn JTAG to GND

    Thanks and best regards,

    Enrique

  • 0 in reply to Enrique Ugarte
    TI__Guru** 106705 points

    What you describe seems to be the 10 pin Cortex Debug connector. This is what we use on the SensorTag and our recommended option. Just be clear, and independent of CC2640 packages, the pinout of the connector is:

    1: VDD-sense
    2: TMS
    3: GND
    4: TCK
    5: GND
    6: TDO
    7: NC
    8: TDI
    9: GND
    10: nReset

  • 0 in reply to Enrique Ugarte
    TI__Mastermind 18780 points

    Note that if using the TPS62730, this provide 2.1 V out so you cannot use external regulator mode (requires supply voltage from 1.7 V- 1.95 V). So if you go with the TPS62730, you must use the normal mode (internal DCDC and/or internal LDO in addition to you regulator).

  • 0 in reply to Fredrik K
    Intellectual 320 points

    Yes in deed it is the Cortex Debug Connector and the pinout you mentioned is correct.

    So, If I place this connector to my PCB and make the wires between the Debug Connector to the CC2640 I will be able to debug/flash my PCB?

    Thanks

  • 0 in reply to Enrique Ugarte
    TI__Mastermind 18780 points
    Yes. With this interface you can use for instant the CC-DEVPACK-DEBUGGER (www.ti.com/.../cc-devpack-debug) or the SmartRF 06EB to program the CC2640 on your PCB.
  • 0 in reply to CHS
    Intellectual 320 points

    Perfect! 

    Thanks a lot!

  • 0 in reply to CHS
    Intellectual 320 points

    One more question, I have finished my PCB design and I just saw something, in the CC2650EM-4XS-Ext_Reg schematic the C22 and C23 capacitors say DNM (Do Not Mount). Why is that? If I don't have to place them in my schematic why are they in the  CC2650EM-4XS-Ext_Reg schematic? Or Should I put them in the schematic but not solder them in the PCB?

    Thanks

  • 0 in reply to Enrique Ugarte
    TI__Guru** 106705 points

    DNM (Do Not Mount) are used when you want the option to potentially place the component later. So you put in the footprint, but does not actually mount the component.


    In this case it is safe to omit the component completely. The crystal will use the internal cap array for load cap.

  • 0 in reply to Fredrik K
    Intellectual 320 points

    Thank you very much for clarifying this.

    Best regards,

    Enrique