Hello,

The FCC test is conducted using CYBT-333047-02 and an antenna different from the reference antenna (B4844-01 etc.) described in the data sheet.

The FCC test has failed the harmonic emission test in BLE.

According to the certification agency, it is possible to correct the transmission power by using the duty ratio of the transmission time in 100 ms in the actual firmware.

So I have a question.

The firmware to use actually uses EZ-Serial.

When transmitting with BLE, Notify and Advertise packet can be considered.

In addition, it is necessary to request the duty of the packet to be sent under the following conditions.

・Observe the transmission packet of one channel when Frequency Hopping is effective.

・Frequency hopping is performed at each Connection Interval, but CH1 appears alternately in hopping (worst case)

　CH1 => CH2 => CH1 => CH3 => CH1 => CH4…

・The Connection Interval and the number of transmitted packets differ depending on iOS/Android

　- iOS: Connection Interval = 30ms / Number of Packets in connection interval = 4 packets

　- Android: Connection Interval = 48.75ms / Number of Packets in connection interval = 6 packets

　- Android(Worst case): Connection Interval = 7.5ms / Number of Packets in connection interval = 6 packets

・Hopping as follows for each Advertisement Interval

　CH37 => CH38 => CH39 => CH37 ...

・EZ-Serial Advertisment Interval default setting is 30ms (0.625ms x48)

　gap_set_adv_parameters (SAP, ID=4/23): H=0x0030 (48)

[Question]

Under the above conditions, I calculated the Tx Duty Cycle as follows.

Is there a mistake in recognition?

1. Notify for iOS (Connection Interval = 30ms / Number of Packets in connection interval = 4 packets)

   - On time: 328us x 8 = 2,624us (2.624ms)

   - Off time: 100,000us - 2,624us = 97,386us (97.386ms)

   Tx Time Duty : 2.624 %

2. Notify for Android (Connection Interval = 48.75ms / Number of Packets in connection interval = 6 packets)

   - On time: 328us x 11 + 110us = 3,718us (3.718ms)

   - Off time: 100,000us - 3,718us = 96,282us (96.282ms)

   Tx Time Duty : 3.718 %

3. Notify for Android - Worst case (Connection Interval = 7.5ms / Number of Packets in connection interval = 6 packets)

   - On time: 328us x 42 = 13,776us (13.776ms)

   - Off time: 100,000us - 13,776us = 86,224us (86.224ms)

  Tx Time Duty : 13.776%

4. Advertisement (Advertisement Interval = 30ms)

   - On time: 328us x 2 = 656us (0.656ms)

   - Off time: 100,000us - 656us = 99,344us (99.344ms)

   Tx Time Duty : 0.656 %

Best regards,

Takahashi

Hello.

Module: CYBT-413034-02

Wiced Studio: 6.4 with MFi

iPad: iPad mini 4, iOS 13.6.1

Sample source: \20719-B1_Bluetooth\apps\demo\apple_mfi\hci_iap2_spp

Changes

LocalName, ExternalAccessoryProtocolName in hci_iap2.c

My experience

Most of cases, Pairing and connection was made well at first time.

But "Reconnection" is issue, most of reconnection try was failed. Or connected for 10~15 seconds and then disconnected.

I also prepare iOS log but I cannot tell appropriate log in console.(Please let me know if you need)

How to recover

When the error happen, I remove the pairing from iPad list, then made connect it was working well.

Snoop log was made with BTSpy.

Reproduce Steps

1. Search and make a connection in iPad settings(bluetooth).

Connection was made in Settings and iPad app connected

(Log 1.pairing_connect_in_app)

2. disconnect from App

(Log 2.disconnect_in_app)

3. disconnect bt connection in iPad settings(bluetooth)

(Log 3.disconnect_in_settgins)

4. Try to connect again in iPad settings(bluetooth)

(Log 4.reconnect_try)

We also have another Bluetooth module(CSR, One of our company's product) and it connect & reconnect well with same iPad and app.

Please review log and provide a solution.