app_ds1722.c - SPI example using the DS1722¶
ESOS application program to demonstrate SPI mastering in ESOS.
Application recreates code in ds1722_spi_tempsense.c in Figure 10.34.
(See Figure 10.31 in the text for circuit.)
Application also has a flashing LED on RB15. Flashing LED is generated by a software timer calling a user-provided callback function.
Note
Demonstrates child tasks, ESOS software timers, and SPI service
- INCLUDEs go here (First include the main esos.h file)
- After that, the user can include what they need
#include "esos.h"
#ifdef __linux
#include "esos_pc.h"
#include "esos_pc_stdio.h"
INCLUDE these so that printf() and our PC hacks work
#include <stdio.h>
#include <sys/select.h>
#include <termios.h>
#include <unistd.h>
#else
#include "esos_pic24.h"
#include "esos_pic24_rs232.h"
#include "esos_pic24_spi.h"
#include <stdio.h>
#endif
DEFINEs go here
//#define PDBG(str) do{printf((str));printf("\n");}while(0)
#define PDBG(str)
#ifndef __linux
#define CONFIG_LED1() CONFIG_RB15_AS_DIG_OUTPUT()
#define LED1 _LATB15
#define CONFIG_SLAVE_ENABLE() CONFIG_RB3_AS_DIG_OUTPUT()
#define SLAVE_ENABLE() _LATB3 = 1 //high true assertion
#define SLAVE_DISABLE() _LATB3 = 0
#else
#define CONFIG_LED1() printf("called CONFIG_LED1()\n")
#define CONFIG_SLAVE_ENABLE() printf("called CONFIG_SLAVE_ENABLE()\n")
#define SLAVE_ENABLE() printf("called SLAVE_ENABLE()\n")
#define SLAVE_DISABLE() printf("called SLAVE_DISABLE()\n")
uint8_t LED1 = TRUE; // LED1 is initially "on"
#endif
PROTOTYPEs go here
void configSPI1(void);
- GLOBALs go here
- Generally, the user-created semaphores will be defined/allocated here
char psz_CRNL[3]= {0x0D, 0x0A, 0};
char psz_prompt[] = "Temp is ";
char psz_done[9]= {' ','D','O','N','E','!',0x0D, 0x0A, 0};
int16_t i16_temp;
ESOS_SEMAPHORE(sem_dataReady);
ESOS_SEMAPHORE(sem_dataPrinted);
ESOS_SEMAPHORE(sem_ds1722Ready);
#ifdef __linux
- Simulate the timer ISR found on a MCU
- The PC doesn’t have a timer ISR, so this task will periodically call the timer services callback instead. USED ONLY FOR DEVELOPMENT AND TESTING ON PC. Real MCU hardware doesn’t need this task
ESOS_USER_TASK( __simulated_isr ) {
ESOS_TASK_BEGIN();
while (TRUE) {
call the ESOS timer services callback just like a real H/W ISR would
__esos_tmrSvcsExecute();
ESOS_TASK_WAIT_TICKS( 1 );
} // endof while(TRUE)
ESOS_TASK_END();
} // end child_task
#endif
/************************************************************************
* User supplied functions
************************************************************************
*/
An ESOS software timer callback function strobe the heartbeat LED.
Toggles LED1 everytime the callback is called. Exact period is determined by application when this timer callback function is registered with ESOS. See ref esos_RegisterTimer Application can change timer period on-the-fly with ref esos_ChangeTimerPeriod
note Since this heartbeat is performed in an ESOS software timer callabck, a flashing LED indicates that the ESOS system tick ISR is being called properly. If the LED quits flashing, then the ESOS system tick has ceased working. This probably indicates some catastrophic failure of the system. However, the cause could be poorly-behaved user code that is manipulating the hardware registers with the timer or interrupt enables directly. ESOS provides functions to change state of interrupts and user code should never modify the hardware used by ESOS to implement the system tick. hideinitializer
user-created timer callback
ESOS_USER_TIMER( swTimerLED ) {
LED1 = !LED1;
#ifdef __linux
if (LED1) {
printf("\a");
fflush(stdout);
}
#endif
} //endof swTimerLED
user task to setup DS1722 for temperature conversion. Will signal when DS1722 is ready to be used.
ESOS_USER_TASK(start_ds1722) {
ESOS_TASK_BEGIN();
configSPI1();
configure DS1722 for 12-bit mode, continuous conversion
ESOS_TASK_WAIT_ON_AVAILABLE_SPI();
SLAVE_ENABLE(); //assert chipselect
ESOS_TASK_WAIT_ON_WRITE2SPI1(0x80, 0xE8);
SLAVE_DISABLE(); //deassert chipselect
ESOS_TASK_SIGNAL_AVAILABLE_SPI();
wait for first conversion to finish, then let other tasks proceed
ESOS_TASK_WAIT_TICKS(1500);
ESOS_SIGNAL_SEMAPHORE(sem_ds1722Ready, 1);
ESOS_TASK_END();
} //end task start_ds1722
user task to read DS1722 SPI temerature sensor
ESOS_USER_TASK(read_ds1722) {
static uint16_t u16_lo, u16_hi;
static uint16_t au16_data[3];
ESOS_TASK_BEGIN();
ESOS_TASK_WAIT_SEMAPHORE(sem_ds1722Ready, 1);
while (TRUE) {
There are (at least) three different ways to cause the DS1722 to read the temperature. Choose one of the following:
#if 0
SLAVE_ENABLE(); //assert chipselect ESOS_TASK_WAIT_ON_WRITE1SPI1(0x01); // LSB address ESOS_TASK_WAIT_ON_READ2SPI1(u16_lo, u16_hi); SLAVE_DISABLE(); //deassert chipselect
#endif
#if 0
SLAVE_ENABLE(); //assert chipselect ESOS_TASK_WAIT_ON_WRITE1SPI1(0x01); // LSB address ESOS_TASK_WAIT_ON_READ1SPI1(u16_lo); ESOS_TASK_WAIT_ON_READ1SPI1(u16_hi); SLAVE_DISABLE(); //deassert chipselect
#endif
#if 1
au16_data[0]= 0x01;
au16_data[1]= 0x00;
au16_data[2]= 0x00;
ESOS_TASK_WAIT_ON_AVAILABLE_SPI();
SLAVE_ENABLE();
ESOS_TASK_WAIT_ON_XFERNSPI1(&au16_data[0],&au16_data[0],3);
SLAVE_DISABLE();
ESOS_TASK_SIGNAL_AVAILABLE_SPI();
u16_hi = au16_data[2];
u16_lo = au16_data[1];
#endif
i16_temp = ((u16_hi<<8) | u16_lo);
ESOS_SIGNAL_SEMAPHORE(sem_dataReady, 1);
ESOS_TASK_WAIT_TICKS(1500);
ESOS_TASK_WAIT_SEMAPHORE(sem_dataPrinted, 1);
} //end while()
ESOS_TASK_END();
} //end task read_ds1722
User task to display temperature results from DS1722. Used printf and floating point for convenience. A production application would likely create custom functions to avoid including these huge libraries.
ESOS_USER_TASK(update) {
float f_tempC, f_tempF;
ESOS_TASK_BEGIN();
while (TRUE) {
ESOS_TASK_WAIT_SEMAPHORE(sem_dataReady, 1);
f_tempC = (float) i16_temp; //convert to floating point
f_tempC = f_tempC/256; //divide by precision
f_tempF = f_tempC*9/5 + 32;
printf("Temp is: 0x%0X, %4.4f (C), %4.4f (F)\n", i16_temp, (double) f_tempC, (double) f_tempF);
ESOS_SIGNAL_SEMAPHORE(sem_dataPrinted, 1);
} // end while(TRUE)
ESOS_TASK_END();
} // end update()
void configSPI1(void) {
//spi clock = 40MHz/1*4 = 40MHz/4 = 10MHz
SPI1CON1 = SEC_PRESCAL_1_1 | //1:1 secondary prescale
PRI_PRESCAL_4_1 | //4:1 primary prescale
CLK_POL_ACTIVE_HIGH | //clock active high (CKP = 0)
SPI_CKE_OFF | //out changes inactive to active (CKE=0)
SPI_MODE8_ON | //8-bit mode
MASTER_ENABLE_ON; //master mode
#if (defined(__dsPIC33E__) || defined(__PIC24E__))
//nothing to do here. On this family, the SPI1 port uses dedicated
//pins for higher speed. The SPI2 port can be used with remappable pins.
#else
//all other families (PIC24H/PIC24F/dsPIC33F)
CONFIG_SDO1_TO_RP(RB6_RP); //use RB6 for SDO
CONFIG_RB6_AS_DIG_OUTPUT(); //Ensure that this is a digital output
CONFIG_SCK1OUT_TO_RP(RB7_RP); //use RB7 for SCLK
CONFIG_RB7_AS_DIG_INPUT(); //Ensure that this is a digital input
CONFIG_SDI1_TO_RP(RB5_RP); //use RP5 for SDI
CONFIG_RB5_AS_DIG_INPUT(); //Ensure that this is a digital input
#endif
CONFIG_SLAVE_ENABLE(); //chip select for MCP41xxx
SLAVE_DISABLE(); //disable the chip select
SPI1STATbits.SPIEN = 1; //enable SPI mode
}
/****************************************************
* user_init()
****************************************************
*/
void user_init(void) {
Call the hardware-provided routines to print the HELLO_MSG to the screen. Must use this call because the ESOS communications subsystems is not yet fully initialized, since this call is in user_init()
In general, users should call hardware-specific function like this.
__esos_unsafe_PutString( HELLO_MSG );
#ifdef __linux
register our little ESOS task to mimic MCU’s TIMER T1 IRQ which kicks off the ESOS S/W timers when they expire
esos_RegisterTask( __simulated_isr );
#endif
configure our hardware to support to support our application
CONFIG_LED1();
ESOS_INIT_SEMAPHORE(sem_ds1722Ready, 0);
ESOS_INIT_SEMAPHORE(sem_dataReady, 0);
ESOS_INIT_SEMAPHORE(sem_dataPrinted, 0);
user_init() should register at least one user task
esos_RegisterTask(start_ds1722);
esos_RegisterTask(read_ds1722);
esos_RegisterTask(update);
register our callback function with ESOS to create a software timer
esos_RegisterTimer( swTimerLED, 250);
} // end user_init()