Many extended chips are parallel input or output, latches or buffer is 8 bit or 16 bit data, is there any way to extend the gpio for single gpio operation, other extensions hole stay latched, truly achieve microcontroller gpio

CodePudding user response:

Hardware structure is different, why, do you know about MCU internal structure that is not visible, should make up a missed lesson.

CodePudding user response:

You can see the 8155 data, a typical extension of the belt latches RAM and IO

CodePudding user response:

Simple extension of the IO 74 hc125 may have a look, forget what is the suffix of belt, 125 c with no deposit, 125 d with the stored? Can't remember

CodePudding user response:

Through the software to realize individual IO operation

CodePudding user response:

reference dceacho reply: 3/f

simple extension of IO 74 hc125 may have a look, forget what is the suffix of belt, 125 c with no deposit, 125 d with the stored? Can't remember

Is 74 hc595 are needed to bring the latches

CodePudding user response:

Any MCU IO mouth first, in the form of the entire byte or word or double word, IO also itself has a port on the structure of latch function, the so-called alone modify (control) an IO port status on micro equivalent to "on the port latch register only modify one", this is not easy, is divided into the following several ways:
1. Itself have READ - the MODIFY - WRITE function, such as the MCS - 51 (including compatible chips) and Microchip PIC (including compatible chips) can be directly to port operations, or by ANL direct, # XXX/ORL direct, # XXX directly modified such instructions,
2. Itself does not have this function but the IO port (the entire 8,16,32) does not change the input and output functions in global (input is always input, the output is always output), then you can read to the accumulator on software or other register, write back to port after the modification of the bit,
3. Itself does not have this kind of function and the IO mouth there is individual port will change the input and output function, you can make a port with variable, modify the output to modify the variable synchronous write out again,