CC2541 Breakout Board

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This wiki presents a compact breakout board design for the CC2541. It includes breakout headers for all GPIO pins, 32kHz sleep crystal and PCB antenna. The board is designed to be run off a single liion cell, but other power sources may also be used.

The Design is made in Eagle CAD which can be downloaded for free, and both design files and manufacturing files are freely available and can be downloaded at the bottom of this page.

CC2541 Breakout Board

Design Description

The CC2541 part of the design is more or less a copy of the CC2541EM with breakout pads for all GPIOs and a 1.27mm pitch debug header for debugging and programming. There is a placeholder for a 0-ohm resistor (R2) between pin 1 and pin 9 of the debug header to enable the debugger to power the board. A 32kHz crystal is included to enable the use of power modes.

The board is originally made to be powered from a single liion cell so the design includes an LM3658 liion battery charger circuit. The LM3658 accepts both USB power or DC voltage between 4.5 V and 6 V. The charge current is fixed at 500 mA when USB is selected and is variable up to 1 A for DC power by changing the value of R4. Power is applied to header JP5. Only one of R10 and R11 should be mounted based on the chosen power source (mounting both will not damage the chip, but it will assume DC power is applied, not USB). Refer to the LM3658 datasheet for further details. The status pins of LM3658 can be connected to P1_6 and P1_7 on CC2541 by mounting R5 and R6.

Power connected directly to the LDO

The power from the battery is regulated down to 3 V by the TPS71530. If not liion is to be used the power source can be connected directly to the input pin of this LDO. The input range will then be approximately 3.5 V to 24 V.

The LDO and liion charger IC can of course both be omitted and power supplied directly to the CC2541 through header JP4. The input range will then be 2 V - 3.6 V.

The antenna used in the design is described in application note AN043.

For Bill of Materials (BOM) refer to the CC2541EM reference design. All other components are non-critical with respect to tolerances etc.

Please note that this is not an official reference design from Texas Instruments. The board has been assembled and the functionality has been confirmed, but it has not been through RF characterization or any other forms of rigorous testing. Care should be taken when using liion batteries as these can be unstable if used improperly. Using liion cells with built-in protective circuits is highly recommended.


External Links

Eagle CAD - Free PCB design software.
Fusion PCB Service - PCB service from Seeed Studio. Used to manufacture the first CC2541 Breakout Boards.