- What are the recommendations for TR mounting regarding ground planes on a mother PCB?
All metallic parts (including ground planes) should be as far as possible from the antenna. See Relative decrease of RF input signal vs. antenna edge spacing to conductive areas chapter in the TR module datasheet.
- What are the requirements for TR sealing?
In case of sealing or protecting TR modules against a harsh environment by coating, encapsulating or potting using a lacquer, gel or other filling matter, the ion cleanliness of the TR modules must be less than 1 µg/cm2 of NaCl equivalent otherwise there is a risk of corrosion.
Such a surface treatment always impacts the RF range. Thus, sealing material should have the relative permeability (µr) as close to 1 within given frequency band. E.g. µr=4 at 868 MHz decreases relative range to approx. 70%.
Protecting materials, methods, accomplishments and handling must comply with general requirements and rules for proper use with electronic devices. Damaging, either chemical or mechanical (even due to the thermal expansivity of the material used) must be avoided. Testing is necessary to ensure that the application meets the specifications.
Recommended coating material: BECTRON MR 3404.
- What are the rules and recommendations for TR SMT mounting?
Refer to Application note AN010 - SMT mounting of IQRF TR modules.
- What are the recommendations for integration of TR-76D into the user’s HW?
Recommended circuit for development is available in the TR datasheet:
- Both LEDs should be used (but need not necessarily be visible outside the case) because it is practical to watch OS and DPA system indication.
- Power supply pins (Vcc and GND), as well as SPI pins, should externally be accessible (e.g. via soldering pads or a single-row connector). If the RFPGM is not applicable or functional for some reason, there will be a possibility to upload TR transceiver using IQRF IDE after connecting CK-USB-04A by wires. See CK-USB-04A User’s guide, chapter In-circuit upload.
- If an external MCU is used, it is recommended to have an option to disconnect the power supply from TR transceiver and disconnect all TR pins by a control signal from this MCU. This allows performing HW reset of TR transceiver in a reliable way. The User’s guide of the KON-RASP-01 kit should serve as an inspiration for this.
- What are the main differences in the usage of SMT TRs like TR-76D and TR-77D?
TR-76D and TR-77D dimensions are reduced as much as possible. No supply voltage regulator is used. Thus, the supply voltage range is 3.0 to 3.4 V and power consumption in sleep in hundreds of nA which is convenient for battery powered applications.
The number of I/Os is extended, pins are not multiplexed. Series protective resistors are recommended for I/O pins.
For solderless prototyping, the DDC-76D-01 development kit is prepared to enable using TR-76D(A) with DK-EVAL-04A and DDC-IO-01 kits.
For in-circuit programming, CK-USB-04A can be used.
- How to protect I/O pins of TRs like TR-76D or TR-77D?
TRs in SIM format (to be operated in SIM connector, e.g. TR-72D) have serial resistors enabling to multiplex more MCU I/Os to one pin and providing a protection. TRs intended for soldering (e.g. TR-76D) have no on-board protection resistors. It is recommended to use protective series resistors 200 ohm on each pin used.