Question about high speed ADC usage

[ahmed]

Hi,

I need to send an audio signal through BLE connection of nRF51822 module, this signal need to quantized and sampled at rate of minimum 8000 sample/second by ADC, i configured the minimum connection interval to 9 ms but the sampling still very low and far from required, i try to decrease the interval below 9 ms but the connection failed. is there any way to increase the sampling rate?

Thanks for your help in this issue

Regards

[RK]

#define 	BLE_GAP_CP_MIN_CONN_INTVL_MIN   0x0006

That's in 1.25ms intervals so 7.5ms is the absolute minimum. That's per BTLE spec.

I don't understand why you refer to increasing 'the sampling rate', doesn't seem like the ADC sampling rate is your problem, it's the BTLE transfer throughput. How are you sending the data, in what sized packets? There's a theoretical maximum of 6 packets per connection interval (I don't recall where that comes from) but it's stated in other questions that many implementations are limited to 4. if you're sending 20 bytes per packet, at 9ms connection interval that's around 8kB/second, if you're only sending one byte per packet, it's about 450 b/second.

And what's on the other end of this link? Just because you request a minimum connection interval of 7.5ms, doesn't mean the master on the other side lets you have it.

[ahmed]

Dear RK,

The UART just use ASCII format, i try to send the 10 bit as integer and get a rubbish characters at terminal program (i receive the data through nRF51 dongle with ble_uart s120 example connected to laptop), then try to send it as hex format and get a separate representative of result ( for example if the ADC result is 1023 i receive 3 254), so i forced to convert it to ASCII. Now, is S120 support transferring 4 packets per connection ? how can i reconfigure the ble_uart S120 example to do this ?

Thanks alot my friend, i appreciate your supporting.

Regards