BSP Developer's Guide

F
Generic Drivers
Define SIO_CALLBACK_GET_TX_CHAR to point to a function that fetches a
new character for output. The driver calls this callback routine with the
supplied argument and an additional argument that is the address to receive
the new output character if any. The called function returns OK to indicate that
a character was delivered, or ERROR to indicate that no more characters are
available.
Define SIO_CALLBACK_PUT_RCV_CHAR to point to a function the driver can
use to send characters upward. For each incoming character, the callback
routine is called with the supplied argument, and the new character as a
second argument. Drivers normally do not care about the return value from
this call. There is usually nothing that the driver could do but to drop a
character if the higher level is not able to receive it.
pollInput and pollOutput
Provide an interface to polled mode operations of the driver. Do not call these
functions unless the device has already been placed into polled mode
operation by an SIO_MODE_SET operation.
See target/src/drv/sio/templateSio.c for more information on the internal
workings of a typical SIO device driver.
F.4 Timer
F
The generic timer drivers reside in the directory target/src/drv/timer. Included in
this directory is templateTimer.c. When writing a timer driver, base the driver on
this template, then modify the BSP’s sysLib.c file to include the driver as needed.If
a BSP has access to only a single timer, that BSP must support the system clock and
not the auxiliary clock. This means that sysAuxClkConnect( ) must return
ERROR.
The following macros are used for parameter checking in VxWorks timer drivers,
and must be defined in each BSP’s bspname.h file:
SYS_CLK_RATE_MIN
Defines the minimum rate at which the system clock can run. Unless hardware
constraints dictate otherwise, SYS_CLK_RATE_MIN must be less than or equal
to 60 Hz.
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