16 bit PWM using CCP1

[EarlyBird2]

your version cannot work since CCP1CON and CCPR1H are not in bank 0

and yes the code you marked red serves no purpose in the given example

My point was that the code in red stopped it working and I could not work out why it was there.

[richard]

the code in red just wastes time ,it's not what stopped the program from working . the problem is the changing sfr's in the wrong bank.

[EarlyBird2]

the code in red just wastes time ,it's not what stopped the program from working . the problem is the changing sfr's in the wrong bank.

It did stop it working on my 18F452 though.

[richard]

bsf INTCON,7 ;GIE = 1
bsf INTCON,6 ;PEIE = 1 Enable peripheral interrupts
bsf PIE1,0 ; TMR1IE= 1 Enable TMR1

intcon bits 6 and 7 should already be set , setting them again should do no harm
pie1.0 is also set , setting it again can't hurt

it just wastes 12 cpu cycles

the problem lies elsewhere, PWM_VAL must be > 30 ,values from 0-29 wont work could that have happened

[EarlyBird2]

intcon bits 6 and 7 should already be set , setting them again should do no harm
pie1.0 is also set , setting it again can't hurt

That is exactly what I thought and could not find anything to indicate otherwise in the datasheet.

the problem lies elsewhere, PWM_VAL must be > 30 ,values from 0-29 wont work could that have happened

No I started PWM_VAL for zero and incremented up in steps of 1 and it worked all the way rolling over and starting from 0. If 0-29 does not work I could not detect it with my voltmeter.

[richard]

just tried your "red" code in the isr on a pic18f45k20

you are right

bsf INTCON,6 ;PEIE = 1 Enable peripheral interrupts
bsf PIE1,0 ; TMR1IE= 1 Enable TMR1
these two lines lock it up. can't see why yet

it looked harmless but its not ,its much worse than useless

[richard]

N

o I started PWM_VAL for zero and incremented up in steps of 1 and it worked all the way rolling over and starting from 0. If 0-29 does not work I could not detect it with my voltmeter

I'm using a cro those <30ish pwm's cause the output pin to be permanently high when you expect a very small pw , in real life that could be nasty
try a loop range yourself of 0 to say 28

[EarlyBird2]

The point of coming here is to learn and I am now comparing the architecture of the 18F452 and the 16F1827. They are completely different, not surprise there.

I have found the sfrs are in bank 5 on the 16F1827 but I have no idea how to use this information.

[EarlyBird2]

N
I'm using a cro those <30ish pwm's cause the output pin to be permanently high when you expect a very small pw , in real life that could be nasty
try a loop range yourself of 0 to say 28

Just tried it no problem 0 gave 0 volts 9 gave 3 mV.

[richard]

CALLS TO ASM always set bank 0

pbp has a macro you can use "chk?rp sfr" it will ckeck that the appropriate bank is set (see status or bank sfr)
the mpasm assembler can also do a " BANKSEL SFR"

BEFORE YOU RETURN T0 PBP YOU MUST SET BANK BACK TO BANK 0

[richard]

not on a cro

using a main loop like this
MAIN:

PWM_VAL = PWM_VAL+1
PAUSE 500
if pwm_val > 29 then pwm_val=0
toggle portd.1
Goto MAIN

[EarlyBird2]

not on a cro

What is a cro?

[richard]

oscilloscope

depending on your age , in the old days a cathode ray oscilloscope, cro for short

[EarlyBird2]

N
I'm using a cro those <30ish pwm's cause the output pin to be permanently high when you expect a very small pw , in real life that could be nasty
try a loop range yourself of 0 to say 28

I will take your word for it as I have no instrument that will replicate your results, and as I have found in the past just because I can not see it does not mean it is not there.

[richard]

the 30 figure came from the pic16f1825 using dt_ints14
for a pic18f45k20 the figure is 25 using dt_ints18
for a pic18f45k20 using DEFINE INTHAND the figure is 11
seems dt_ints introduces more latency

point is 0 is not off and pwm < latency is not a small pw

[talatsahim]

your version cannot work since CCP1CON and CCPR1H are not in bank 0

and yes the code you marked red serves no purpose in the given example

Richard,
Thanks for your reply.
Yes, you're right. 103 error occurs after compiling. Banksel command is used, will you?

Talat

[talatsahim]

Thanks
Yes, you're right.
My first version was like you, did not work. To better understand the problem I have added including red lines.
I tried again and the result is the same version. In the start-up process produces two pulses and then stops.

[talatsahim]

I installed the PBP trial version 3.0.7 to try. Nothing's changed. Error 113 continues (Post 56, I wrote 103, it's wrong)

[HenrikOlsson]

Hi,
Check your spelling of CCPR1H and CCPR1L.

/Henrik.

[talatsahim]

Hi,
Henrik, congratulations for being careful, thank you.
This is a completely copy-paste disaster
Talat

[EarlyBird2]

Hi,
Henrik, congratulations for being careful, thank you.
This is a completely copy-paste disaster
Talat

That error comes from post #35 and #37 is there anyway these posts can be corrected?