Cristian Castro / Mbed 2 deprecated 08-Nucleo446_V2HX711

Lectura de una celda de Carga HX711.

Dependencies:   mbed

Hx711.cpp@1:392a3fb6d177, 2021-09-03 (annotated)

Committer:
CCastrop1012
Date:
Fri Sep 03 04:51:59 2021 +0000
Revision:
1:392a3fb6d177
Lectura de una celda de Carga.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
CCastrop1012 1:392a3fb6d177 1 #include "mbed.h"
CCastrop1012 1:392a3fb6d177 2 #include "Hx711.h"
CCastrop1012 1:392a3fb6d177 3
CCastrop1012 1:392a3fb6d177 4 void Hx711::set_gain(uint8_t gain) {
CCastrop1012 1:392a3fb6d177 5 switch (gain) {
CCastrop1012 1:392a3fb6d177 6 case 128: // channel A, gain factor 128
CCastrop1012 1:392a3fb6d177 7 gain_ = 1;
CCastrop1012 1:392a3fb6d177 8 break;
CCastrop1012 1:392a3fb6d177 9 case 64: // channel A, gain factor 64
CCastrop1012 1:392a3fb6d177 10 gain_ = 3;
CCastrop1012 1:392a3fb6d177 11 break;
CCastrop1012 1:392a3fb6d177 12 case 32: // channel B, gain factor 32
CCastrop1012 1:392a3fb6d177 13 gain_ = 2;
CCastrop1012 1:392a3fb6d177 14 break;
CCastrop1012 1:392a3fb6d177 15 }
CCastrop1012 1:392a3fb6d177 16
CCastrop1012 1:392a3fb6d177 17 sck_.write(LOW);
CCastrop1012 1:392a3fb6d177 18 read();
CCastrop1012 1:392a3fb6d177 19 }
CCastrop1012 1:392a3fb6d177 20
CCastrop1012 1:392a3fb6d177 21 uint32_t Hx711::readRaw() {
CCastrop1012 1:392a3fb6d177 22 // wait for the chip to become ready
CCastrop1012 1:392a3fb6d177 23 // TODO: this is not ideal; the programm will hang if the chip never
CCastrop1012 1:392a3fb6d177 24 // becomes ready...
CCastrop1012 1:392a3fb6d177 25 while (!is_ready());
CCastrop1012 1:392a3fb6d177 26
CCastrop1012 1:392a3fb6d177 27 uint32_t value = 0;
CCastrop1012 1:392a3fb6d177 28 uint8_t data[3] = { 0 };
CCastrop1012 1:392a3fb6d177 29 uint8_t filler = 0x00;
CCastrop1012 1:392a3fb6d177 30
CCastrop1012 1:392a3fb6d177 31 // pulse the clock pin 24 times to read the data
CCastrop1012 1:392a3fb6d177 32 data[2] = shiftInMsbFirst();
CCastrop1012 1:392a3fb6d177 33 data[1] = shiftInMsbFirst();
CCastrop1012 1:392a3fb6d177 34 data[0] = shiftInMsbFirst();
CCastrop1012 1:392a3fb6d177 35
CCastrop1012 1:392a3fb6d177 36 // set the channel and the gain factor for the next reading using the clock pin
CCastrop1012 1:392a3fb6d177 37 for (unsigned int i = 0; i < gain_; i++) {
CCastrop1012 1:392a3fb6d177 38 sck_.write(HIGH);
CCastrop1012 1:392a3fb6d177 39 sck_.write(LOW);
CCastrop1012 1:392a3fb6d177 40 }
CCastrop1012 1:392a3fb6d177 41
CCastrop1012 1:392a3fb6d177 42 // Datasheet indicates the value is returned as a two's complement value
CCastrop1012 1:392a3fb6d177 43 // Flip all the bits
CCastrop1012 1:392a3fb6d177 44 data[2] = ~data[2];
CCastrop1012 1:392a3fb6d177 45 data[1] = ~data[1];
CCastrop1012 1:392a3fb6d177 46 data[0] = ~data[0];
CCastrop1012 1:392a3fb6d177 47
CCastrop1012 1:392a3fb6d177 48 // Replicate the most significant bit to pad out a 32-bit signed integer
CCastrop1012 1:392a3fb6d177 49 if ( data[2] & 0x80 ) {
CCastrop1012 1:392a3fb6d177 50 filler = 0xFF;
CCastrop1012 1:392a3fb6d177 51 } else if ((0x7F == data[2]) && (0xFF == data[1]) && (0xFF == data[0])) {
CCastrop1012 1:392a3fb6d177 52 filler = 0xFF;
CCastrop1012 1:392a3fb6d177 53 } else {
CCastrop1012 1:392a3fb6d177 54 filler = 0x00;
CCastrop1012 1:392a3fb6d177 55 }
CCastrop1012 1:392a3fb6d177 56
CCastrop1012 1:392a3fb6d177 57 // Construct a 32-bit signed integer
CCastrop1012 1:392a3fb6d177 58 value = ( static_cast<uint32_t>(filler) << 24
CCastrop1012 1:392a3fb6d177 59 | static_cast<uint32_t>(data[2]) << 16
CCastrop1012 1:392a3fb6d177 60 | static_cast<uint32_t>(data[1]) << 8
CCastrop1012 1:392a3fb6d177 61 | static_cast<uint32_t>(data[0]) );
CCastrop1012 1:392a3fb6d177 62
CCastrop1012 1:392a3fb6d177 63 // ... and add 1
CCastrop1012 1:392a3fb6d177 64 return static_cast<int>(++value);
CCastrop1012 1:392a3fb6d177 65 }
CCastrop1012 1:392a3fb6d177 66
CCastrop1012 1:392a3fb6d177 67
CCastrop1012 1:392a3fb6d177 68 uint8_t Hx711::shiftInMsbFirst() {
CCastrop1012 1:392a3fb6d177 69 uint8_t value = 0;
CCastrop1012 1:392a3fb6d177 70
CCastrop1012 1:392a3fb6d177 71 for (uint8_t i = 0; i < 8; ++i) {
CCastrop1012 1:392a3fb6d177 72 sck_.write(HIGH);
CCastrop1012 1:392a3fb6d177 73 value |= dt_.read() << (7 - i);
CCastrop1012 1:392a3fb6d177 74 sck_.write(LOW);
CCastrop1012 1:392a3fb6d177 75 }
CCastrop1012 1:392a3fb6d177 76 return value;
CCastrop1012 1:392a3fb6d177 77 }