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diff --git a/doc/bsp_howto/analog.t b/doc/bsp_howto/analog.t deleted file mode 100644 index 094f4cbcd3..0000000000 --- a/doc/bsp_howto/analog.t +++ /dev/null @@ -1,163 +0,0 @@ -@c -@c COPYRIGHT (c) 1988-2002. -@c On-Line Applications Research Corporation (OAR). -@c All rights reserved. - -@chapter Analog Driver - -The Analog driver is responsible for providing an -interface to Digital to Analog Converters (DACs) and -Analog to Digital Converters (ADCs). The capabilities provided -by this class of device driver are: - -@itemize @bullet -@item Initialize an Analog Board -@item Open a Particular Analog -@item Close a Particular Analog -@item Read from a Particular Analog -@item Write to a Particular Analog -@item Reset DACs -@item Reinitialize DACS -@end itemize - -Most analog devices are found on I/O cards that support multiple -DACs or ADCs on a single card. - -There are currently no analog device drivers included in the -RTEMS source tree. The information provided in this chapter -is based on drivers developed for applications using RTEMS. -It is hoped that this driver model information can form the -basis for a standard analog driver model that can be supported -in future RTEMS distribution. - -@section Major and Minor Numbers - -The @b{major} number of a device driver is its index in the -RTEMS Device Address Table. - -A @b{minor} number is associated with each device instance -managed by a particular device driver. An RTEMS minor number -is an @code{unsigned32} entity. Convention calls for -dividing the bits in the minor number down into categories -like the following: - -@itemize @bullet - -@item @b{board} - indicates the board a particular device is located on -@item @b{port} - indicates the particular device on a board. - -@end itemize - -From the above, it should be clear that a single device driver -can support multiple copies of the same board in a single system. -The minor number is used to distinguish the devices. - -@section Analog Driver Configuration - -There is not a standard analog driver configuration table but some -fields are common across different drivers. The analog driver -configuration table is typically an array of structures with each -structure containing the information for a particular board. -The following is a list of the type of information normally required -to configure an analog board: - -@table @b -@item board_offset -is the base address of a board. - -@item DAC_initial_values -is an array of the voltages that should be written to each DAC -during initialization. This allows the driver to start the board -in a known state. - -@end table - -@section Initialize an Analog Board - -At system initialization, the analog driver's initialization entry point -will be invoked. As part of initialization, the driver will perform -whatever board initialization is required and then set all -outputs to their configured initial state. - -The analog driver may register a device name for each DAC and ADC in -the system. - -@section Open a Particular Analog - -This is the driver open call. Usually this call does nothing other than -validate the minor number. - -With some drivers, it may be necessary to allocate memory when a particular -device is opened. If that is the case, then this is often the place -to do this operation. - -@section Close a Particular Analog - -This is the driver close call. Usually this call does nothing. - -With some drivers, it may be necessary to allocate memory when a particular -device is opened. If that is the case, then this is the place -where that memory should be deallocated. - -@section Read from a Particular Analog - -This corresponds to the driver read call. After validating the minor -number and arguments, this call reads the indicated device. Most analog -devices store the last value written to a DAC. Since DACs are output -only devices, saving the last written value gives the appearance that -DACs can be read from also. If the device is an ADC, then it is sampled. - -@b{NOTE:} Many boards have multiple analog inputs but only one ADC. On -these boards, it will be necessary to provide some type of mutual exclusion -during reads. On these boards, there is a MUX which must be switched -before sampling the ADC. After the MUX is switched, the driver must -delay some short period of time (usually microseconds) before the -signal is stable and can be sampled. To make matters worse, some ADCs -cannot respond to wide voltage swings in a single sample. On these -ADCs, one must do two samples when the voltage swing is too large. -On a practical basis, this means that the driver usually ends up -double sampling the ADC on these systems. - -The value returned is a single precision floating point number -representing the voltage read. This value is stored in the -@code{argument_block} passed in to the call. By returning the -voltage, the caller is freed from having to know the number of -bits in the analog and board dependent conversion algorithm. - -@section Write to a Particular Analog - -This corresponds to the driver write call. After validating the minor -number and arguments, this call writes the indicated device. If the -specified device is an ADC, then an error is usually returned. - -The value written is a single precision floating point number -representing the voltage to be written to the specified DAC. -This value is stored in the @code{argument_block} passed in to the -call. By passing the voltage to the device driver, the caller is -freed from having to know the number of bits in the analog -and board dependent conversion algorithm. - -@section Reset DACs - -This is one of the IOCTL functions supported by the I/O control -device driver entry point. When this IOCTL function is invoked, -all of the DACs are written to 0.0 volts. - -@section Reinitialize DACS - -This is one of the IOCTL functions supported by the I/O control -device driver entry point. When this IOCTL function is invoked, -all of the DACs are written with the initial value configured -for this device. - -@section Get Last Written Values - -This is one of the IOCTL functions supported by the I/O control -device driver entry point. When this IOCTL function is invoked, -the following information is returned to the caller: - -@itemize @bullet -@item last value written to the specified DAC -@item timestamp of when the last write was performed -@end itemize - |