/ Mbed OS L432KC_SPI_Pey_Lal

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https://www.mediafire.com/file/sjhxgn70gxshilg/protocol_spi_pwm.png/file

protocol.cpp@111:f11575e7c79b, 2022-04-07 (annotated)

Committer:
voltxd
Date:
Thu Apr 07 12:30:01 2022 +0000
Revision:
111:f11575e7c79b
Parent:
110:a6d1d3525014 
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Who changed what in which revision?

UserRevisionLine numberNew contents of line
voltxd 110:a6d1d3525014 1 #include "protocol.h"
voltxd 110:a6d1d3525014 2
voltxd 110:a6d1d3525014 3 char newDataAvailable = 0;
voltxd 110:a6d1d3525014 4
voltxd 111:f11575e7c79b 5 //Bytewise XOR
voltxd 110:a6d1d3525014 6 char calculateChecksum(uint32_t propulsion, uint32_t direction)
voltxd 110:a6d1d3525014 7 {
voltxd 110:a6d1d3525014 8 char checksum = 0xff;
voltxd 110:a6d1d3525014 9 checksum ^= propulsion >> 8;
voltxd 110:a6d1d3525014 10 checksum ^= propulsion & (0b11111111);
voltxd 110:a6d1d3525014 11 checksum ^= direction >> 8;
voltxd 110:a6d1d3525014 12 checksum ^= direction & (0b11111111);
voltxd 110:a6d1d3525014 13
voltxd 110:a6d1d3525014 14 return checksum;
voltxd 110:a6d1d3525014 15 }
voltxd 110:a6d1d3525014 16
voltxd 110:a6d1d3525014 17 char receiveState = STATE_START_OF_FRAME;
voltxd 110:a6d1d3525014 18 char receiveIndex = 0;
voltxd 110:a6d1d3525014 19 uint32_t receivedPropulsion;
voltxd 110:a6d1d3525014 20 uint32_t receivedDirection;
voltxd 110:a6d1d3525014 21
voltxd 110:a6d1d3525014 22 uint32_t verifiedPropulsion = 1500;
voltxd 110:a6d1d3525014 23 uint32_t verifiedDirection = 1150;
voltxd 110:a6d1d3525014 24
voltxd 111:f11575e7c79b 25 //Decode the bytes received according to their order of reception.
voltxd 110:a6d1d3525014 26 void decodeMessage(char c)
voltxd 110:a6d1d3525014 27 {
voltxd 110:a6d1d3525014 28 switch(receiveState)
voltxd 110:a6d1d3525014 29 {
voltxd 110:a6d1d3525014 30 case STATE_START_OF_FRAME:
voltxd 110:a6d1d3525014 31 //Checking if we received the start Byte
voltxd 110:a6d1d3525014 32 if (c == 0xff)
voltxd 110:a6d1d3525014 33 {
voltxd 110:a6d1d3525014 34 receiveState = STATE_PROPULSION;
voltxd 110:a6d1d3525014 35 receiveIndex = 0;
voltxd 110:a6d1d3525014 36 }
voltxd 110:a6d1d3525014 37 break;
voltxd 110:a6d1d3525014 38
voltxd 110:a6d1d3525014 39 case STATE_PROPULSION:
voltxd 110:a6d1d3525014 40 //Retrieving the propulsion PWM bytes (1. MSB; 2. LSB)
voltxd 110:a6d1d3525014 41 if (receiveIndex++ == 0)
voltxd 110:a6d1d3525014 42 receivedPropulsion = c << 8;
voltxd 110:a6d1d3525014 43 else
voltxd 110:a6d1d3525014 44 {
voltxd 110:a6d1d3525014 45 receivedPropulsion += c;
voltxd 110:a6d1d3525014 46 receiveState = STATE_DIRECTION;
voltxd 110:a6d1d3525014 47 receiveIndex = 0;
voltxd 110:a6d1d3525014 48 }
voltxd 110:a6d1d3525014 49 break;
voltxd 110:a6d1d3525014 50
voltxd 110:a6d1d3525014 51 case STATE_DIRECTION:
voltxd 110:a6d1d3525014 52 //Retrieving the direction PWM bytes (1. MSB; 2. LSB)
voltxd 110:a6d1d3525014 53 if (receiveIndex++ == 0)
voltxd 110:a6d1d3525014 54 receivedDirection = c << 8;
voltxd 110:a6d1d3525014 55 else
voltxd 110:a6d1d3525014 56 {
voltxd 110:a6d1d3525014 57 receivedDirection += c;
voltxd 110:a6d1d3525014 58 receiveState = STATE_CHECKSUM;
voltxd 110:a6d1d3525014 59 }
voltxd 110:a6d1d3525014 60 break;
voltxd 110:a6d1d3525014 61
voltxd 110:a6d1d3525014 62 case STATE_CHECKSUM:
voltxd 110:a6d1d3525014 63 //Checksum
voltxd 110:a6d1d3525014 64 if (c == calculateChecksum(receivedPropulsion, receivedDirection))
voltxd 110:a6d1d3525014 65 {
voltxd 111:f11575e7c79b 66 //The frame is correct, we can use the values retrieved.
voltxd 110:a6d1d3525014 67 verifiedPropulsion = receivedPropulsion;
voltxd 110:a6d1d3525014 68 verifiedDirection = receivedDirection;
voltxd 110:a6d1d3525014 69 newDataAvailable = 1;
voltxd 110:a6d1d3525014 70 }
voltxd 110:a6d1d3525014 71 receiveState = STATE_START_OF_FRAME;
voltxd 110:a6d1d3525014 72 break;
voltxd 110:a6d1d3525014 73
voltxd 110:a6d1d3525014 74 default:
voltxd 110:a6d1d3525014 75 receiveState = STATE_START_OF_FRAME;
voltxd 110:a6d1d3525014 76 break;
voltxd 110:a6d1d3525014 77 }
voltxd 110:a6d1d3525014 78 }
voltxd 110:a6d1d3525014 79
voltxd 111:f11575e7c79b 80 //Return the values decoded
voltxd 110:a6d1d3525014 81 void getVerifiedPWMValues(uint32_t *pwmPropulsion, uint32_t *pwmDirection)
voltxd 110:a6d1d3525014 82 {
voltxd 110:a6d1d3525014 83 *pwmPropulsion = verifiedPropulsion;
voltxd 110:a6d1d3525014 84 *pwmDirection = verifiedDirection;
voltxd 110:a6d1d3525014 85 newDataAvailable = 0;
voltxd 110:a6d1d3525014 86 }
voltxd 110:a6d1d3525014 87
voltxd 111:f11575e7c79b 88 //Return a value telling if new informations are available.
voltxd 110:a6d1d3525014 89 char isDataAvailable()
voltxd 110:a6d1d3525014 90 {
voltxd 110:a6d1d3525014 91 return newDataAvailable;
voltxd 110:a6d1d3525014 92 }