Utilizing Cypress's EZ-BLE modules in Custom PCB Designs

Created by Matthew Bon, last modified on Nov 21, 2016

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Introduction:

Cypress Semiconductor’s EZ-BLE modules are a series of complete Bluetooth Low Energy transceivers based on Cypress’s PROC and PSOC 4 BLE chips. These modules greatly simplify product design by eliminating the RF board design, and significantly reducing the certification and qualification processes required for BLE enabled products.

This article seeks to explain the differences between the various EZ-BLE modules as well as provide relevant information for using these modules in PCB designs.

Useful Links :

Cypress EZ-BLE Page

Cypress App Note: AN96841 Getting Started With EZ-BLE Module

Cypress App Note: AN91445 Antenna Design and RF Layout Guidelines

EZ-BLE Modules Quick Reference:

Model Number Device BLE Revision Flash (KB) Dimensions (mm) Antenna GPIO Digikey Part number
CYBLE-022001-00 PROC 4.1 128 10 x 10 x 1.8 Chip 16 428-3408-1-ND
CYBLE-014008-00 PSOC 4 BLE 4.1 128 11 x 11 x 1.8 PCB 25 428-3600-1-ND
CYBLE-012011-00 PROC 4.1 128 14.5 x 19.2 x 2.0 PCB 23 428-3537-1-ND
CYBLE-012012-10* PROC N/A 128 14.5 x 19.2 x 1.6 PCB 23 428-3538-1-ND
CYBLE-222005-00 PROC 4.1 256 10 x 10 x 1.8 Chip 16 428-3755-1-ND
CYBLE-222014-01 PROC 4.2 256 10 x 10 x 1.8 Chip 16 428-3583-1-ND
CYBLE-212019-00 PROC 4.1 256 14.5 x 19.2 x 2.0 PCB 23 428-3810-1-ND
CYBLE-212023-10* PROC N/A 256 14.5 x 19.2 x 2.0 PCB 23 428-3811-1-ND
CYBLE-214009-00 PSOC 4 BLE 4.1 256 11 x 11 x 1.8 PCB 25 428-3809-ND
CYBLE-224110-00 PSOC 4 BLE 4.1 256 9.5 x 15.4 x 1.8 Chip 25 N/A

*The CYBLE-012012-10 and CYBLE-212023-10 do not contain a RF shield and are not certified by the Bluetooth SIG or any regulatory agencies. The certified versions of these two module are the CYBLE-01201-00 and CYBLE-212019-00 respectively.

Cypress BLE Dev Kits and Evaluation Modules Quick Reference:

Model Number Part/Module BLE Revision Digikey Part Number
CY8CKIT-042-BLE Pioneer Kit CY8C4247LQI-BL483 and CYBL10563-56LQXI 4.1 428-3349-ND
CY8CKIT-042-BLE-A Pioneer Kit CY8C4248LQI-BL583 and CYBL11573-56LQXI 4.2 428-3804-ND
CYBLE-022001-EVAL CYBLE-022001-00 4.1 428-3406-ND
CYBLE-014008-EVAL CYBLE-014008-00 4.1 428-3429-ND
CYBLE-012011-EVAL CYBLE-012011-00 4.1 428-3525-ND
CYBLE-222005-EVAL CYBLE-222005-00 4.1 428-3536-ND
CYBLE-222014-EVAL CYBLE-222014-01 4.2 428-3584-ND
CYBLE-212019-EVAL CYBLE-212019-00 4.1 428-3601-ND
CYBLE-214009-EVAL CYBLE-214009-00 4.1 428-3602-ND
CYBLE-224110-EVAL CYBLE-224110-00 4.1 428-3802-ND

The CY8CKIT-042-BLE and CY8CKIT-042-BLE-A Pioneer kits contain a baseboard which all the the evaluation modules listed above plug into. This baseboard supplies power to the module, breaks out the module’s I/O pins to a set of Arduino compatible headers and serves as the programmer/debugger for the module.

External Components:

While the EZ-BLE modules integrate nearly every component required for a complete BLE transceiver solution, there are still a few components that must be included external to the module in order to ensure proper operation.

Ferrite Beads:

The most critical of these components is the ferrite bead which is crucial to ensuring that noise does not couple into the power system of the EZ-BLE module.

The PROC based EZ-BLE modules have two power pins (VDD and VDDR). VDD is for the digital sub-system and VDDR is for the radio’s power supply. The PSOC 4 based modules have three power pins, (VDD, VDDR and VDDA), where VDDA is the power pin for the analog sub system. If the designer intends to supply all the power pins with a single voltage supply, Cypress recommends one of the following setups.

Ferrite Bead Placement for PROC based Modules

*Image courtesy of CYBLE-022001-00 Datasheet Rev 7, page 10

Ferrite Bead Placement for PSOC based Modules

Image courtesy of CYBLE-214009-00 Datasheet Rev *C, page 11

Obviously the single ferrite bead option is cheaper since it only uses one bead. However, the multiple ferrite bead option has the advantage of preventing any noise generated by one of the sub-systems from coupling through the power lines into the other sub-system. Thus, if greater noise immunity is desired, the multiple ferrite bead option should be used. Regardless of the setup used, the designer should try to place the ferrite bead(s) as close as possible to the power pins.

If the designer is using separate voltage supplies for each sub-system, each pin should have its own ferrite bead.

As can be seen in the figure above, the recommended impedance value at least 300 Ohms at 100 MHz. An example of a suitable bead would be the Laird MI0805L301R-10 or the Murata BLM21PG331SN1D .

Capacitors:

None of the capacitors listed below are technically necessary for the module to work. However depending on the application, they may need to be included in order to ensure full functionality of the module

  • Capacitor on the reset line (XRES) - The reset pin on the EZ-BLE modules is active low. In noisy environments, it might be necessary to include a small filter cap on the reset line in order to prevent unintended resets. 0.1uF is a typical value for this capacitor, though a different value may be necessary depending on the environment. This capacitor should be connected between the XRES line and ground.

  • Capsense Capacitors- If the designer intends on using Cypress’s Capsense capacitive touch sensing technology, up to four external capacitors may be needed (Cmod, Csh_tank, Cinta and CintB). Which capacitors need to be included depends on type of capacitive sensing is being used. Some of the EZ-BLE modules include some of these capacitors on the module itself; the table below details which modules contain the capsense capacitors. More details on implementing capsense can be found in Cypress app note AN85951

Module Capsense Capacitors Included
CYBLE-022001-00 None
CYBLE-014008-00 Cmod, Ctank
CYBLE-012011-00 None
CYBLE-012012-10 None
CYBLE-222005-00 None
CYBLE-222014-01 None
CYBLE-212019-00 None
CYBLE-212023-10 None
CYBLE-214009-00 Cmod, Ctank
CYBLE-224110-00 Cmod, Ctank

Design Considerations for Optimum RF Performance:

While the EZ-BLE modules eliminate most of the headaches involved with designing wireless products. It is still necessary to take care in designing the product to ensure maximum RF performance.

  • The primary consideration to keep in mind is that the EZ-BLE modules each use a monopole antenna which requires that no ground or signal traces are placed under the antenna itself. In addition, the PCB area within several millimeters of the antenna should also be free of ground and signal traces. Each EZ-BLE module will specify the size of the required keep-out area in its datasheet.

  • In addition, monopole antennas also need a solid ground plane in order to work properly. This ground plan should be located within several millimeters of the antenna, but outside the keep-out area mentioned above.

  • Typically, the best performance will be achieved when the module is located on the corner of the PCB, away from the rest of the circuitry.

  • Antenna polarization is typically not a major issue with these modules since they usually operate in indoor environments where reflections are common. However for the best performance, the module should be orientated so that its antenna matches the polarization of the antenna on the device that it is trying to communicate with. In practice, this generally means orientating the module the same direction as the module that its trying to communicate with, (i.e. if one module is orientated horizontally with respect to earth’s surface, then the other module should be orientated horizontally as well).

  • The module should not be enclosed in a metallic enclosure. If a metallic enclosure needs to be used, the enclosure should not cover the antenna on the module.

  • If a non-metallic enclosure is used, there should be at least 5mm of space between the module and the enclosure.

  • Metallic objects should not be placed within 6.2 mm of the top of the antenna or 8mm of the sides of the antenna.

For a more detailed explanation of module placement and suitable enclosures, the reader should consult section 7 of Cypress app note AN96841 listed in the “Useful Links” section above.

Eagle Library & Kicad Footprints:

Below is a component library for Eaglecad containing symbols and footprints for all the EZ-BLE modules listed in the quick-reference table above. There is also a folder containing footprints for each of the EZ-BLE modules in the .Kicad_mod file format.

The files below are unofficial and not have been verified or reviewed by Cypress Semiconductor or anyone other than the author of this article. It is highly recommended that the user takes time to review the footprints before using them in their own design

Eagle Library: Digikey_EZ_BLE.zip

Kicad Footprints: Digikey_EZ_BLE.pretty.zip