Diversion: What is Sound Anyway?
This post is discusses some interesting properties of sound itself, not all of which can be easily measured. This is …
Author Archives: rberteig
Improved audio recording from the PDM microphone connected to an LPC812
This post continues experimenting with recording audio converted from PDM to PCM in an LPC812 CPU. The last installment passed …
Recording PCM audio from the PDM microphone connected to an LPC812
This post continues experimenting with the PDM conversion to PCM samples in an LPC812 CPU. From the earlier tests we …
Source Code for the LPC812 PDM SPL is online
I updated the fossil PDMStunts repository to include source code for computing SPL from PDM microphone data as described in …
Testing the PDM to SPL arithmetic
Since porting the PDM microphone SPL measurement code base from the ATTiny85 to the ARM based LPC8xx family, it would …
An RTOS for an 8-pin ARM CPU
While researching another post recently, I tripped over an impressively small RTOS (real time operating system) that can be built …
PDM to SPL Demonstrated in an LPC810
This post demonstrates the SPL meter described earlier running in an NXP LPC810 ARM CORTEX-M0+ microprocessor. The computed SPL level …
PDM in another 8-pin CPU
This post explores interfacing a PDM microphone with an NXP LPC810 ARM CORTEX-M0 microprocessor, taking advantage of its existing peripherals …
SPL is Logarithmic
In this post, we discuss why we represent SPL on a logarithmic scale, why you should care, and how we …
PDM in ATTiny85 Source Code
This is part of a series of articles on the general subject of audio signal processing from air to information. …
Words from Cheshire Engineering Corp. 