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diff --git a/docs/parts/ioport.md b/docs/parts/ioport.md new file mode 100644 index 0000000..96a4b82 --- /dev/null +++ b/docs/parts/ioport.md @@ -0,0 +1,167 @@ +IO port +======= +And define: `CONFIG_IOE_IOPORT` + +Defines simple access to io ports. This allows runtime access to any pin with just +serialized identifier. + +Most of the functions has group and mask arguments. Group is letter, but in this +library is represented as number and exact number is defined as macro definition. +Mask is one shifted by index number(use \_BV macro). This way can be +addressed all IO ports. Exact identification consult with datasheet. You can also +use more than one index number and control more ports in single group with single +command. + +WARNING: No check is implemented for right group number. Usage of unsupported +value is undefined (write to other parts of memory can happen). + +Configuration +------------- +To use this part, you must enable `CONFIG_IOPORTS` option. +This part also handles pin change interrupts. Enable it using +`CONFIG_IOPORTS_PCINT` option. + +References +---------- +### For output +#### Function io_setout +```C +static inline void io_setout(uint8_t group, uint8_t mask) +``` +Configures port of `group` with `mask` as output. +Parameters: +__group__ - Character specifying exact port group +__mask__ - Binary shifted 1. Shift is equal to port index in specified group. + +#### Function io_hight +```C +static inline void io_hight(uint8_t group, uint8_t mask) +``` +Sets output port to hight (also can be called as 1). +WARNING: Invoke this only if io_setout is called before. + +Parameters: +__group__ - Character specifying exact port group +__mask__ - Binary shifted 1. Shift is equal to port index in specified group. + +#### Function io_low +```C +static inline void io_low(uint8_t group, uint8_t mask) +``` +Sets output port to low (also called as 0). +WARNING: Invoke this only if io_setout is called before. + +Parameters: +__group__ - Number specifying exact port group +__mask__ - Binary shifted 1. Shift is equal to port index in specified group. + +#### Function io_set +```C +static inline void io_set(uint8_t group, uint8_t mask, int8_t val) +``` +Sets output port to value passed as argument. +WARNING: Invoke this only if io_setout is called before. +Parameters: +__group__ - Number specifying exact port group +__mask__ - Binary shifted 1. Shift is equal to port index in specified group. + +### For input +#### Function io_setin +```C +static inline void io_setin(uint8_t group, uint8_t mask, + enum ioeIOInResistor resistor) +``` +Configures port of `group` with `mask` as input with specified pull-up/down +resistor. + +Parameters: +__group__ - Number specifying exact port group +__mask__ - Binary shifted 1. Shift is equal to port index in specified group. + +#### Function io_get +```C +static inline int8_t io_get(uint8_t group, uint8_t mask) +``` +Returns current value of port. Note that you can use this also if port is +configured as output. + +Parameters: +__group__ - Number specifying exact port group +__mask__ - Binary shifted 1. Shift is equal to port index in specified group. + +#### Enum ioeIOInResistor +```C +enum ioeIOInResistor { + IOE_IO_PULLUP, + IOE_IO_PULLDOWN +}; +``` +This enum is used as argument for io_setin. Names should be self explanatory +in this case. + +### Pin change interrupts +#### Function io_change_sethook +```C +int8_t io_change_sethook(uint8_t group, uint8_t mask, uint8_t edge, + void (*change) (uint8_t group, uint8_t mask)) +``` +Registers function `change` as hook for pin change interrupt. `group` and `mask` +specifies port and edge specifies on what edge should hook be called. `edge` can +be IO_RISING or IO_FALLING or their binary combination with operator +`|`. +WARNING: `change` call is call during interrupt handling. You shouldn't be +blocking execution for long time. + +Parameters: +__group__ - Number specifying exact port group. +__mask__ - Binary shifted 1. Shift is equal to port index in specified group. +__edge__ - Signals on what edge should be hook called. +__change__ - Pointer to function used as interupt hook. + +#### Function io_change_remhook +```C +int8_t io_change_remhook(void (*change) (uint8_t group, uint8_t mask)) +``` +Removes `change` hook. + +Parameters: +__change__ - Pointer to function used as hook + +### Others +#### Definitions IO_{GROUP} +This defines exact numbers related to data-sheet groups. Always use these +definition not direct numbers, you can ensure cross MCU support this way. + +#### Definitions IO_{GROUP}{INDEX} +Because specifying group and mask as separate parameters is not always optimal, +mcu support file should define all ports in form of single line definition in +format `IOE_IO_{GROUP}{INDEX}`. Disadvantage is that with these definitions you +can't use binary conjunction and so only one pin can be controlled with it. + +Relevant examples +----------------- +* blink +* pcinterrupt + +Adding support +-------------- +For more information on how add support, see [Adding MCU support](/add_support.md). +Main definition is `MCUSUPPORT_IOPORT`. Define it to enable support. + +### IO_{GROUP} +This should define any number that is handy for implementation of `IOE_IOE_PIN`, +`IOE_IO_DDR` and `IOE_IO_PORT`. + +### IO_{PIN/DDR/PORT} +These should calculate exact pointers to register `PORT{GROUP}` for PORT variant +and likewise for others with group as argument. Common implementation would be +like this: +```C +#define IOE_IO_PIN(GROUP) (* (volatile uint8_t *)(PINB + 0x3*GROUP)) +``` +### IO_{GROUP}{INDEX} +This should be pair of group and one binary shifted to left relative to index. + +### MCUSUPPORT_PCINT{NUM} +This defines that MCU supports specific pin change interrupt group. Also it +defines value that is number of pins in group. |