BC127 / BC127-HD ADC performance

IoT Modules WiFi and Bluetooth Modules
1

I cant find any information about the ADC for the mic / line inputs in the BC127 module.
Can anyone give me some information?
Since the BC127-HD supports 24bit/96k-Audio, is there a better ADC implemented?
I’m developing a bluetooth-boombox with additional line-input and I’m not shure, if the ADC in the BC127 is suitable for the line-input.

Thanks for your help!

2

Sstudi,

The HD is a slightly different hardware build from the standard one and it is all designed to match together, what information are you after?

Regards

Matt

3

Hi there !

I will use this topic as I have related questions.
I cannot find any information regarding ADC input characteristics. Does anyone knows:

  • Input impedance (Single End / Diff)
  • Input voltage for Full Scale output (Single End / Diff)
  • Common mode bias ? (i.e. should inputs be AC coupled, or biased to a level, and which one ?)

I want to use BC127 as a transmitter for line-level analog signal, not microphone. So I have to design my analog front-end to meet specifications (that are absent of the datasheet…)
I do not plan to use the +20dB gain configurable in Melody (dedicated for microphone use)

If anyone can help.
Thanks !

4

Sorry, but nobody did never used the analog input of BC127 ?
Does anybody knows the full scale voltage input ?

Thanks !

5

I went over what I know about the ADC in another post:

The peak to peak full scale input is around 1.6 volts as far as I can tell. The input impedance varies from 6k to 30k depending on the gain setting. For a line level input you’ll want to use a low gain. You should AC couple the inputs.

Set a very low output gain then vary the input gain to find the right level (so you know any overload comes from the input amp).

6

Hi BPT !

Thanks a lot for this answer, this surely helps !

Cheers,

7

Good evening, I apologize immediately but I don’t speak/write English (I use google traduttore). I’m very interested of this discussion.
I have realised a project with BC127 module in transmit mode for send 2 audio channel (stereo) using mic input. My audio souce is an dvd player. The experimet work fine but i have a problem with low frequency 20~200 hz band (i belived). One track of the dvd, is an explosion of bombs and barrage of bullets (matrix 1 :slight_smile: ). The sound from the speakers is very distorcts when the bomb explodes; no problem for barrage of bullets, voice peole, acoustic instruments or other signals etc.
I don’t have the possibility to make an audio swap. I have a doubt. How to connect line audio inputs to bc 127? I use a trimmer (10kohm) to trim audio signal, and a capacitor (4,7uF) to connect at MIC_LP (othel channel to MIC_RP pin), then MIC_LN and MIC_RN to gnd . The bias pin is not connected. Is correct?
It is possible to have an example diagram for connect audio signals. some advice?
Thankyou in advance.

8

Hi @commercialsile,

Welcome you to our community!

Please refer to section 4.4.1 Analog Audio Input: Microphones and 4.4.2 Analog Audio Input: Line In on pages 30 and 31 of the BC127 Product Technical Specification at the following link:

https://source.sierrawireless.com/resources/airprime/hardware_specs_user_guides/airprime_bc127---product-technical-specification/#sthash.3A96frjj.dpbs

Thanks,