 |
 |
| View previous topic :: View next topic |
| Author |
Message |
JohnHopkins
Guest
|
| Sleep and Idle Modes on an 18F4685 |
 Posted: Fri Dec 11, 2009 11:36 am |
 |
|
PIC- 18F4685
Compiler- 4.085
I am trouble with the PIC low power modes.
When I put the PIC in SLEEP mode, it draws microamps.
However, when I put the PIC into IDLE mode, it draws ~ 5 mA, which is about the same as it draws in RUN mode. There appears to be no power saving in IDLE mode. I have all the tristates set to input, so it should not be driving any pins. I also used printfs to check the SFRs and confirm that all the peripherals were off. But it looks like some peripheral is on and consuming power...
I used printfs to confirm that the PIC goes into IDLE mode and never wakes up, since all interrupts are disabled.
Here's a test program:
| Code: | #include <18F4685.h>
#device PASS_STRINGS = IN_RAM
#include <stdio.h>
#include <string.h>
#use delay(INTERNAL=8M, clock=16M)
#fuses INTRC, NOWDT, NOLVP, NOPBADEN, NOBROWNOUT, NOPROTECT//, DEBUG
/////////////////////////////////////////////////////////////////////////////////////////////////////////
//SFRs///////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////////////////////
#byte OSCCON = 0xFD3
#bit IDLEN = OSCCON.7
#byte CCP1CON = 0xFBD
#byte ECCP1CON = 0xFBA
#byte SSPCON1 = 0xFC6
#byte RCSTA = 0xFAB
#byte ADCON0 = 0xFC2
#byte CMCON = 0xFB4
#byte CVRCON = 0xFB5
#byte HLVDCON = 0xFD2
#byte CANSTAT = 0xF6E
//Debug
//#use rs232(BAUD=9600, XMIT=PIN_B3, BITS=8, PARITY=N)
//Main////////////////////////////////////////////////////////////////////////////////////////////////////////
void setup_clk() {
setup_oscillator(OSC_16MHZ);
delay_ms(10);
}
void setup_io() {
//set tris
set_tris_a(0xFF);
set_tris_b(0xFF);
set_tris_c(0xFF);
set_tris_d(0xFF);
set_tris_e(0xFF);
}
void go_to_sleep() {
IDLEN=1;
sleep();
}
void main(void) {
//setup pic
setup_clk();
disable_interrupts(GLOBAL);
setup_io();
CMCON=0;
CANSTAT=0x20;
/* printf("Current Peripheral SFR Status\r\n");
printf("CCP1CON = %X\r\n",CCP1CON);
printf("ECCP1CON = %X\r\n",ECCP1CON);
printf("SSPCON1 = %X\r\n",SSPCON1);
printf("RCSTA = %X\r\n",RCSTA);
printf("ADCON0 = %X\r\n",ADCON0);
printf("CMCON = %X\r\n",CMCON);
printf("CVRCON = %X\r\n",CVRCON);
printf("HLVDCON = %X\r\n",HLVDCON);
printf("CANSTAT = %X\r\n",CANSTAT);*/
while(1) {
// printf("I'm asleep!\r\n");
go_to_sleep();
// printf("I'm awake!\r\n");
}
}
|
Thanks for your help. |
|
 |
JohnHopkins
Guest
|
| Shutting Down CAN |
| Posted: Fri Dec 11, 2009 12:05 pm |
|
|
I just realized that I was trying to disable CAN in CANSTAT, when I should have used CANCON. I made the change, but that didn't solve the problem. However, when I read CANSTAT, it tells me that it is in configuration mode, not disable mode. So it looks like CAN is still on...
| Code: |
#include <18F4685.h>
#device PASS_STRINGS = IN_RAM
#include <stdio.h>
#include <string.h>
#use delay(INTERNAL=8M, clock=16M)
#fuses INTRC, NOWDT, NOLVP, NOPBADEN, NOBROWNOUT, NOPROTECT//, DEBUG
/////////////////////////////////////////////////////////////////////////////////////////////////////////
//SFRs///////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////////////////////
#byte OSCCON = 0xFD3
#bit IDLEN = OSCCON.7
#byte CCP1CON = 0xFBD
#byte ECCP1CON = 0xFBA
#byte SSPCON1 = 0xFC6
#byte RCSTA = 0xFAB
#byte ADCON0 = 0xFC2
#byte CMCON = 0xFB4
#byte CVRCON = 0xFB5
#byte HLVDCON = 0xFD2
#byte CANSTAT = 0xF6E
#byte CANCON = 0xF6F
//Debug
//#use rs232(BAUD=9600, XMIT=PIN_B3, BITS=8, PARITY=N)
//Main////////////////////////////////////////////////////////////////////////////////////////////////////////
void setup_clk() {
setup_oscillator(OSC_16MHZ);
delay_ms(10);
}
void setup_io() {
//set tris
set_tris_a(0xFF);
set_tris_b(0xFF);
set_tris_c(0xFF);
set_tris_d(0xFF);
set_tris_e(0xFF);
}
void go_to_sleep() {
IDLEN=1;
sleep();
}
void main(void) {
//setup pic
setup_clk();
disable_interrupts(GLOBAL);
setup_io();
CMCON=0;
CANCON=0x20;
/* printf("Current Peripheral SFR Status\r\n");
printf("CCP1CON = %X\r\n",CCP1CON);
printf("ECCP1CON = %X\r\n",ECCP1CON);
printf("SSPCON1 = %X\r\n",SSPCON1);
printf("RCSTA = %X\r\n",RCSTA);
printf("ADCON0 = %X\r\n",ADCON0);
printf("CMCON = %X\r\n",CMCON);
printf("CVRCON = %X\r\n",CVRCON);
printf("HLVDCON = %X\r\n",HLVDCON);
printf("CANSTAT = %X\r\n",CANSTAT);*/
while(1) {
// printf("I'm asleep!\r\n");
go_to_sleep();
// printf("I'm awake!\r\n");
}
} |
|
|
|
PCM programmer
Joined: 06 Sep 2003
Posts: 21708
|
|
| Posted: Fri Dec 11, 2009 1:53 pm |
|
|
Your program is too complicated. Also, according to the Electrical
Characteristics section of the 18F4685 data sheet, the speed of the
internal oscillator makes a huge difference in the current consumption
during idle mode. So why not try it with the lowest speed ?
Try the incredibly stripped down program shown below. I don't have
your PIC so I can't test this, but I think it would be a good test.
| Code: |
#include <18F4685.h>
#use delay(INTERNAL=8M, clock=16M)
#fuses INTRC, NOWDT, NOLVP, NOPBADEN, NOBROWNOUT, NOPUT
//======================================
void main(void)
{
setup_oscillator(OSC_IDLE_MODE | OSC_INTRC | OSC_31KHZ);
sleep();
while(1);
}
|
|
|
|
JohnHopkins
Guest
|
| That did the trick |
| Posted: Fri Dec 11, 2009 5:59 pm |
|
|
Thanks for your input. Reducing the clock speed reduced the power consumption by ~90%, so we are good.
Just as a point of interest, we still can't put the CANCON register into Disable mode. The CANSTAT register always indicates that the CAN is in Configuration mode. However, this does not draw a noticeable amount of power at lower frequencies. |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
FAQ 
Search
Register
Profile 
Log in to check your private messages 
Log in
