A simple linux kernel module to drive the August 1996 EA Pocket Sampler.
Some time ago (1999-05-11) Max Lock emailed me about the driver and hardware unit, he was kind enough to email me some PDFs of the kit plans. These are a little more modern than mine, this unit has a precision voltage reference and requires no calibration, identical ADC hardware though.
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A simple linux char device driver was written to talk to the device.
It implements:
Honors O_NONBLOCK and is concurrent read() safe. It should compile on linux 1.2.13, 2.0.3x and 2.2.1x, and most likely will work on later kernels too.
read() Returns lines of 4 integers. The first two are the sample time, epoch seconds, and microseconds (from do_gettimeofday()). The third is the level switch position for that sample (2 or 20 volts). The forth is the raw sample, 0-255.
In single shot mode (see below), a single sample is returned on read(), later reads on the same file descriptor will return 0 bytes readable. In periodic sampling mode, a blocking read() will occur, making the device node appear like a pipe.
write() Writting to the device controls the sampling interval. An integer in plain text is written to the device to change the sampling period. A zero will yield single shot mode, any other value will cause a sample to be taken every 100ms times that value. The default intial value is zero, or single shot mode.
open(), select(), and close() work as expected.
The code is here: eapsampler and eapsampler-2.0.tar.gz
[Back] © 2002 Alan Yates <alany(at)alanyates(dot)com>
