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PurePath CC8531

Igor Dranov
Prodigy 170 points

Other Parts Discussed in Thread: CC8531

Dear, TI Community.
I would like to ask 3 questions.

1. Let's suppose there is wireless stereo headphone (2 audio channel). What quantity of this headphones (with differents sources (Masters)) can work in one room? What will happen if  we switch on one more headphone in this room?

2. Is it possible to create "3+1 system" using CC8531:
a) 4 channel audio data from PC come through USB to Master CC8531.
b) 3 channel audio data are wireless transmitted to Slave (and are played there)
c) 1 channel (4th) audio data is played on Master CC8531.

3. Is it possible to configure CC8531 to receive data by radio if USB is unplugged and to recive data from USB (and radio is switched off) if USB is plugged ?

Sincerely, Igor

  • 0
    TI__Expert 7160 points

    Hi Igor,

    1. The PPW Protocol divides the 2.4 GHz band into 18 RF channels. Each PPW network use 4 of these 18 RF channels. That gives room for 4 networks (4 master slave pairs). Adding a fifth network will cause packet collisions and the frequency hopping in each network will be chaotic. We have tested with 4 networks and that works fine (video here: http://www.ti.com/product/cc8520. Check out the Videos sections at the bottom and the video called "PurePath Wireless Audio Coexistence Test").

    2. It's not possible to have the USB interface and the I2S interface working at the same time. All 4 audio channels from the USB to CC85xx will have to go out on the air (not possible to take one of them out on the master's I2S).

    3. As mentioned in 2) it's not possible to have the USB interface and the I2S interface working at the same time. It's either or, and it requires a re-flash of the device to change this. 

    -Kristoffer

  • 0 in reply to Kristoffer S
    Prodigy 170 points

    Hi Kristoffer,

    1. "Each PPW network use 4 of these 18 RF channels. That gives room for 4 networks (4 master slave pairs)."

    Does it mean that it is possible to use 4 independ networks with 1 master and 4 slaves (slaves with any numbers of channels) in one room? (total: 4 Masters and 16  1-channel-Slaves. Or also total: 4 Masters and 4 4-channel-Slaves)

    (2,3) Does exist any way to render sound on USB Master device without using radio? (with one more MCU or something else). 

    -Igor

     

  • 0 in reply to Igor Dranov
    TI__Expert 7160 points

    Hi Igor,

    1. Yes, in theory each network can max out the number of audio channels (4) and/or the number of slaves (4). So both combinations you mention are in theory possible. However, adding more slaves and adding more audio channels to a network will degrade the overall robustness in this network (possibility of lost samples and mute events will increase). Also, the more networks you put into an environment, the more difficult the RF conditions will be for each network. So for example 1 master-slave-pair using 1 audio channel is a more robust scenario than 2 such networks. There will be more packets lost in the scenario with 2 networks, but it will normally not result in mute events due to the retransmission of lost audio that the protocol does, so you as a listner will not necessarily notice the degraded robustness.

    2,3. No, unfortunatelly.

    Bets regards

    Kristoffer