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Tech FAQ

ANT Hardware

  • How can I set up my device with modulated mode for RF regulatory test?
    • You should check the datasheet to see if the ANT device features this mode; if it’s not present, the easiest way to approximate a constant modulated mode signal is to setup a transmit only channel to broadcast at a fast rate (150-~200Hz for AP1/AP2/C257x).

  • How can I set up my device with no modulated mode for RF regulatory test?
    • ANT has a Continuous Wave (CW) test mode where the radio will transmit continuously without a modulated carrier, using the given transmit power level and channel RF frequency.

  • What are the differences between the AP1 and AT3 chipsets?
    • The nRF24AP1 is the most compact ANT solution with a single IC containing both the protocol as well as the RF transceiver radio. It supports the full synchronous / asynchronous serial interface to an application microcontroller along with all of the features of the ANT protocol. The AP1 supports 4 ANT channels.

      The AT3 chipset includes one ANT MCU, a pairing radio chip (nRF24LO1), and the SensRcore (see sensRcore FAQs for more detail) application development platform which eliminates the need for an application MCU and firmware programming in the design of simple wireless sensors. The AT3 chipsets have 1/4/8 ANT channels and are, so-far, the lowest power consumption solution of ANT.  In summary, the following features are supported by the AT3 family:
      • Scanning channel
      • Inclusion/exclusion list
      • SensRcore
      • Low/high priority search
      • Lower power
      • Unique serial number
      • Baud rate (57,600 bps vs AP1’s 50,000 bps)
      • Channels (up to 8)

  • What is the difference between the ANTAP281M5IB and ANT11TS33M5IB modules?
    • The AT3 (ANT11TS33M5IB) module can be used directly without the need for an external MCU. That is because most AT3 modules feature SensRcore which is an easy-to-use platform for designing wireless networks. This feature allows developers to load scripts into the AT3 module for configuring ANT channels and setting the device as a master or slave.

      Check the product data sheet for your specific AT3 module to see whether or not the module supports SensRcore feature.However, SensRcore is only suitable for very simple wireless network applications. Therefore, whether or not you need an external MCU depends on the complexity of your application.

      For more information on how to use SensRcore in an AT3 module, refer to the ANT Development Kit User Manual.

  • Is there any reference for the RF design and PCB layout? Can I get support on RF antenna design and tuning services?
    • Yes, the PCB layout reference design is available for both Nordic semi and TI products. Nordic and TI’s reference designs support a 50 ohm stub and they also suggest a meandering antenna design. Please contact your local Nordic or TI distributor to ask them for layout assistance help and circuit testing. Nordic typically offers these services to their customers free of charge.

  • What benefits can I get when select using the ANT modules?
    • Based on chipsets or single chips, ANT modules offer a complete wireless solution with RF circuitry and optimized antenna design for your products and applications, reducing the need for RF expertise.

      the product has enough space to contain the module, it will simplify the hardware design and provide a much faster time to market. When the product goes to mass production, you can consider cost of induction to replace it with single chip.


  • What are the differences between the nRF24AP1 and the nRF24AP2?
    • Based on the nRF24L01+ radio platform, the nRF24AP2 provides significant sensitivity and co-existence performance improvements compared to nRF24AP1. It supports all of the messages and features that the nRF24AP1 does, as well as many that are unsupported by the AP1; the main differences are:
      • High density node support – up to 300 nodes at 1 Hz Tx rate in same RF space
      • Frequency agility
      • Proximity search
      • Scanning mode – extremely low latency for asynchronous applications such as remote control
      • Low priority search – does not impact existing active channels
      • Channel ID management – improve device pairing efficiency
      • Individual output power control per channel
      • 10x lower power consumption
      • Better RF preference .

  • Which features are hardware dependent?
    • All ANT modules and chipsets have different product capabilities. These differences are listed under Appendix A of the ANT Message Protocol and Usage document, in the “ANT Message Summary”  and “ANT Product Capabilities” tables. 

      If the product is a slave device which requires high resolution RSSI (such as minimum proximity pairing distance), the CC257x chip or C7 module and the nRF51422 or N5 module should be considered.

  • What are the differences between the nRF24AP2 and the CC257x?
    • The CC257x family is the first ANT network processor solution from TI (Texas Instruments), it supports all of the messages and features that the nRF24AP2 does, as well as many that are unsupported by the nRF24AP2; the main differences are:

      • Integrated ANT-FS Client (additional EEPROM chip required)
      • File System management
      • AES-128 encryption
      • +4dBm transmit RF power
      • High resolution raw RSSI information reading (minimum pairing distance isa about 10cm; the nRF24AP2 does not support raw RSSI  information and relies only upon proximity search bins, thus the minimum pairing distance is about 70cm  using bin 1)
      • The power consumption is about 20% higher than the AP2.

  • I’d like to try and save on BOM costs, do I need an external crystal in my hardware design?
    • An external 32.768 kHz crystal with +/- 50 PPM accuracy or better should always be used for optimum functionality.

      Some ANT capable devices include an internal 32.768 kHz oscillator with accuracy worse than +/-50 PPM. While this internal oscillator may appear to work under ideal, quiet wireless conditions for a single ANT channel, the channel will be far less robust in real world environments as compared to running with an external crystal.

      1. An internal oscillator can be sensitive to temperature changes, so calibration would need to occur more often when the error spikes due to changes in the environment, causing timing issues and increased power consumption.
      2. An error greater than +/-50PPM will mean that ANT channel transmissions could always fall outside of the normally expected timing window, which is conceptually reserved for ANT channel coexistence. While for a single ANT master channel in a quiet environment this would appear to work fine, this means that in noisy environments (or environments with many active ANT master channels like ANT+ in a training gym), the transmitter(s) would interfere with one another far more often, and cause issues with timing collisions over the air.
      3. If the PPM happens to skew fully in opposite directions on the transmitting/receiving devices, then the channel may drop periodically as well, and search period durations could also be extended.

      This ANT Application Note goes into some further discussion on the detrimental effects of poor clock accuracy, as well as a tool to help test the accuracy of your existing hardware.