Electrum Kernel SPI ADC Driver - Revision history

Support: /* Kernel SPI ADC driver */

Support — Mon, 14 Nov 2011 13:47:53 GMT

Kernel SPI ADC driver

← Older revision		Revision as of 13:47, 14 November 2011
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	=Kernel SPI ADC driver=		=Kernel SPI ADC driver=

-	* [http://www.micromint.com/updates/electrum/adc128s052.zip adc128s052.zip]	+	* [http://www.micromint.com/updates/electrum/adc128s052.zip adc128s052.zip] Updated: Nov-2011
	Contributed by: Christian Saether		Contributed by: Christian Saether

Support at 23:02, 2 February 2011

Support — Wed, 02 Feb 2011 23:02:46 GMT

← Older revision		Revision as of 23:02, 2 February 2011
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-	=Kernel SPI ADC driver ~~by Christian Saether~~=	+	=Kernel SPI ADC driver=

	* [http://www.micromint.com/updates/electrum/adc128s052.zip adc128s052.zip]		* [http://www.micromint.com/updates/electrum/adc128s052.zip adc128s052.zip]
		+	Contributed by: Christian Saether

	This driver is an spi protocol driver for the adc128s052 a/d chip option on the Micromint Electrum 100 SBC.		This driver is an spi protocol driver for the adc128s052 a/d chip option on the Micromint Electrum 100 SBC.

Support: Created page with '=Kernel SPI ADC driver by Christian Saether= * [http://www.micromint.com/updates/electrum/adc128s052.zip adc128s052.zip] This driver is an spi protocol driver for the adc128s05…'

Support — Wed, 02 Feb 2011 18:13:27 GMT

Created page with '=Kernel SPI ADC driver by Christian Saether= * [http://www.micromint.com/updates/electrum/adc128s052.zip adc128s052.zip] This driver is an spi protocol driver for the adc128s05…'

New page

=Kernel SPI ADC driver by Christian Saether=

* [http://www.micromint.com/updates/electrum/adc128s052.zip adc128s052.zip]

This driver is an spi protocol driver for the adc128s052 a/d chip option on the Micromint Electrum 100 SBC.
It is meant to be built as a loadable driver.
It allocates a megabyte internal buffer (about a second's worth of samples) when loaded. It is controlled by writing to its file system device.

The commands are:

"r" - run
"s" - stop
"cddd..." - one or more "d" specifying channel rotation

It will send a message to sample each of the specified channels 16 times in rotation.
Channel zero is always included. The numbers of channels must be 1, 2, 4, or 8.

For example, if the device is "/dev/adc0" then the following shell command

echo c0123 > /dev/adc0

will enable sampling for channels 0, 1, 2, and 3. The device must be stopped when this is issued. To start sampling, do

echo r > /dev/adc0

At this point, the data samples will be returned by doing a read on /dev/adc0. They are returned as a series of 16 bit values in the channel rotation specified.

Using od to display them, for example:

od -sAn -w8 /dev/adc0
8172 8174 1 268
8174 8181 1 270
8172 8181 2 266
8176 8173 0 263
8172 8172 2 268
8172 8179 2 265
8169 8177 2 269
8175 8180 1 264

Reading from minor device numbers other than zero will average samples by 2 raised to the minor number, so reading minor device number 1 returns the average of every 2 samples, minor 2 every 4 samples, up to minor 4 (avg every 16). Values from the a/d are shifted left 2 (multiplied by 4) as the lower bits will have some value when multiple samples are averaged.