Arnaud VALLEY / Mbed 2 deprecated Pinscape_Controller_V2_arnoz

Mirror with some correction

Dependencies:   mbed FastIO FastPWM USBDevice

TinyDigitalIn/TinyDigitalIn.h@116:7a67265d7c19, 2021-10-01 (annotated)

Committer:
arnoz
Date:
Fri Oct 01 08:19:46 2021 +0000
Revision:
116:7a67265d7c19
Parent:
82:4f6209cb5c33 
- Correct information regarding your last merge

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mjr 73:4e8ce0b18915 1 #include "mbed.h"
mjr 73:4e8ce0b18915 2
mjr 48:058ace2aed1d 3 // TinyDigitalIn - a simpler verison of DigitalIn that takes less
mjr 48:058ace2aed1d 4 // memory.
mjr 48:058ace2aed1d 5 //
mjr 48:058ace2aed1d 6 // This version uses the same mbed library infrastructure as the
mjr 73:4e8ce0b18915 7 // regular DigitalIn, but we save a little memory by storing only
mjr 48:058ace2aed1d 8 // the minimum set of fields needed to read the pin. The mbed
mjr 48:058ace2aed1d 9 // DigitalIn has a larger memory footprint because it stores the
mjr 48:058ace2aed1d 10 // full set of machine register pointers for the pin, most of
mjr 48:058ace2aed1d 11 // which aren't needed for an input-only pin.
mjr 48:058ace2aed1d 12
mjr 48:058ace2aed1d 13 class TinyDigitalIn
mjr 48:058ace2aed1d 14 {
mjr 48:058ace2aed1d 15 public:
mjr 73:4e8ce0b18915 16 TinyDigitalIn(PinName pin) { assignPin(pin); }
mjr 73:4e8ce0b18915 17 TinyDigitalIn() { assignPin(NC); }
mjr 73:4e8ce0b18915 18
mjr 73:4e8ce0b18915 19 void assignPin(PinName pin)
mjr 48:058ace2aed1d 20 {
mjr 48:058ace2aed1d 21 if (pin != NC)
mjr 48:058ace2aed1d 22 {
mjr 48:058ace2aed1d 23 // initialize the pin as a GPIO Digital In port
mjr 48:058ace2aed1d 24 gpio_t gpio;
mjr 48:058ace2aed1d 25 gpio_init_in(&gpio, pin);
mjr 48:058ace2aed1d 26
mjr 48:058ace2aed1d 27 // get the register input port and mask
mjr 48:058ace2aed1d 28 pdir = gpio.reg_in;
mjr 73:4e8ce0b18915 29 uint32_t mask = gpio.mask;
mjr 73:4e8ce0b18915 30
mjr 73:4e8ce0b18915 31 // Figure the bit shift: find how many right shifts it takes
mjr 73:4e8ce0b18915 32 // to shift the mask bit into the 0th bit position. This lets
mjr 73:4e8ce0b18915 33 // us pull out the result value in read() as a 0 or 1 by shifting
mjr 73:4e8ce0b18915 34 // the register by this same amount and masking it against 0x01.
mjr 73:4e8ce0b18915 35 // The right shift is slightly more efficient than a conditional
mjr 73:4e8ce0b18915 36 // to convert a bit in the middle of the register to a canonical
mjr 73:4e8ce0b18915 37 // 0 or 1 result, and we have to do the mask anyway to pull out
mjr 73:4e8ce0b18915 38 // the one bit, so this makes the overall read slightly faster.
mjr 73:4e8ce0b18915 39 for (shift = 0 ;
mjr 73:4e8ce0b18915 40 mask != 0 && (mask & 0x00000001) == 0 ;
mjr 73:4e8ce0b18915 41 mask >>= 1, shift++) ;
mjr 73:4e8ce0b18915 42 }
mjr 73:4e8ce0b18915 43 else
mjr 73:4e8ce0b18915 44 {
mjr 73:4e8ce0b18915 45 // not connected - point to a dummy port that always reads as 0
mjr 73:4e8ce0b18915 46 pdir = (volatile uint32_t *)&pdir_nc;
mjr 73:4e8ce0b18915 47 shift = 0;
mjr 73:4e8ce0b18915 48 }
mjr 48:058ace2aed1d 49 }
mjr 48:058ace2aed1d 50
mjr 73:4e8ce0b18915 51 inline int read() { return (*pdir >> shift) & 0x00000001; }
mjr 48:058ace2aed1d 52 inline operator int() { return read(); }
mjr 48:058ace2aed1d 53
mjr 77:0b96f6867312 54 protected:
mjr 73:4e8ce0b18915 55 volatile uint32_t *pdir; // pointer to GPIO register for this port
mjr 73:4e8ce0b18915 56 uint8_t shift; // number of bits to shift register value to get our port bit
mjr 73:4e8ce0b18915 57
mjr 73:4e8ce0b18915 58 // pointer to dummy location for NC ports - reads as all 1 bits,
mjr 73:4e8ce0b18915 59 // as though it were wired to a pull-up port that's not connected
mjr 73:4e8ce0b18915 60 // to anything external
mjr 73:4e8ce0b18915 61 static const uint32_t pdir_nc;
mjr 73:4e8ce0b18915 62 } __attribute__((packed));