This shared library will allow easy access to integrated circuits with the
I²C-bus interface. Note that this archive contains *only* the source code.
If you haven't already done so, please also take a look at the
documentation from the original distribution, in hard/hack/i2clib40.lha
How to build the libraries
--------------------------
These sources are intended for use with A68k and BLink (both available from
Aminet) and the system assembler includes (exec/types.i and such) from the
NDK.
If you've got all that, you will probably still need to edit line 3 in the
"make" script so that it points to the real location of your include files.
After that you can build a particular library, let's say i2c.library.disk
for example, by typing
> make disk
and then call the "install" script to use it:
> install disk
Other useful commands are "make all", which builds all versions of the
library, and "make clean", which will delete all library binaries again.
Note that for the implementation of "all", the scripts assume that for each
library called "i2c.library.type", an include file called "type.i" exists
in the source directory.
If you are going to use an assembler other than A68k, please be aware that
there are no include statements for the "type.i" files in the source code.
Their use is controlled from the "make" script, using A68k's -h option.
Making modifications
--------------------
Multitasking access to global objects in the library is protected by a
semaphore, this applies to I/O operations on the I2C bus in particular.
Please be careful if you need to touch the semaphore code. Make a mistake
and the library clients will hang or trash each other's data.
Other than that, the workings of the library are rather straightforward and
reasonably well documented, so good luck.
Known bugs
----------
In the parallel and serial port versions of the library, some
intializations are performed at the wrong time: Open() calls InitI2C(),
which then executes the INITPORT macro, and in these versions of the
library, that forces both I2C lines to HI. This means that a new client
opening the library may corrupt another client's ongoing transmission.
I think that a clean and simple solution would be to postpone this
initialization until the bus is actually needed, like it is done in the
disk version of the library, for example, with the ALLOCPERCALL macro. I
never bothered to fix this, however, because the practical impact of the
bug seems to be rather low, and because I had other things to do.
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