by 5B4AIY » 16 Dec 2017 07:44
Hi, John,
Taking another look, if you were to use a plug-in daughter board using the voice memory option connector, you have access to the audio in/out, microphone in/out as well as the SPI bus, and thus there is a possibility of incorporating an advanced DSP module without any surgery, or, at most only a minor amount. Take a look at the voice memory option board schematics.
As the firmware, including mine, accesses and controls the voice memory module, this could be re-designed and re-written as a DSP control module. The problem comes when you try to integrate a user interface - there are simply no more push buttons available, and even my firmware makes full use of both primary and secondary button functions for all the existing buttons.
To attempt to incorporate a third level function would certainly pose a challenge, it would depend on just how much user control of a DSP module would be required apart from configuration and setup. These actions could easily be incorporated into the existing calibration and setup and user configuration menus.
So, without even modifying the existing clocking arrangements, if a plug-in DSP daughter board were designed to use the existing voice memory option connector, and if this board incorporated its own microprocessor and was controlled via the existing SPI bus, then very little hardware modifications would be necessary, and the DSP controls could be incorporated into the existing firmware.
To see what existing firmware modifications would be required, take a look at my firmware, and in particular the isd1700.c voice memory control module, as well as the various button logic modules, and the calibration and setup, and user configuration routines to give you an idea of how to extend these for DSP setup.
Food for thought?
73, Adrian, 5B4AIY