If you have an oscilloscope then use it. It gives better information than an LED at high frequencies.

Write a main loop to toggle an LED without using delay.
Show your code and report back.

The program in #54 is for the simulator.

 

If you have an oscilloscope then use it. It gives better information than an LED at high frequencies.

Write a main loop to toggle an LED without using delay.
Show your code and report back.

Hi Mr C,
I have an oscilloscope, but I also have a simulator, shown here, which is good for this sort of thing.
Here it shows the Program and result:
C

 

Receiver is not enabled.
It gets now the interrupt from other source, probably TX interrupt.
You should setup the receiver, look #54
Setup the interrupts only for the receiver.

Hi J,
Is this correct? I'm not sure about the BRG settings.
C.

 

This is a barebones Oshonsoft simulator demo to receive a message by interrupts.
No checking of errors, overflows, message start characters etc.
You have to do the hard work.

'**** Oshonsoft Basic Simulation for USART Rx with interrupts
'PIC8LF4620 8MHz

Define SIMULATION_WAITMS_VALUE = 1 
Define CLOCK_FREQUENCY = 8

'*** Setup interrupts ***

RCON.IPEN = 1  'IPEN: Int Priority Enable bit 'This MUST be included when using Interrupts (Priority HIGH/LOW)[#189 hserin blocking]
PIE1 = %00100000  'RCIE: EUSART Receive Interrupt Enable bit [ 1=en ]
INTCON.PEIE = 1  'PEIE/GIEL: Peripheral Interrupt Enable bit
INTCON.GIE = 1  'GIE/GIEH: Global Interrupt Enable bit *** s

' **** Setup Hw USART ****
Hseropen 9600  

Dim char As Byte
Dim str1(20) As Byte ' *** received message comes to str1
Dim rxi As Byte    ïndex to Str1
Dim msg_rdy As Bit

rxi = 0
msg_rdy = 0
Enable High

Main:
Break  '***stop and put a short msg ending with "!" in to Simulator Rx window

While not msg_rdy // **** the real program can run here and check msg_rdy as needed
Wend

Break  '**** stop, now the Str1 can be looked at the variable window

End                                              

On High Interrupt
Save System

If PIR1.RCIF = 1 Then
  char = RCREG
  str1(rxi) = char
  rxi = rxi + 1
Endif

If char = "!" Then  ' ***  ends the message ****
  msg_rdy = 1
Endif
Resume

 

This is a barebones Oshonsoft simulator demo to receive a message by interrupts.
No checking of errors, overflows, message start characters etc.
You have to do the hard work.

'**** Oshonsoft Basic Simulation for USART Rx with interrupts
'PIC8LF4620 8MHz

Define SIMULATION_WAITMS_VALUE = 1
Define CLOCK_FREQUENCY = 8

'*** Setup interrupts ***

RCON.IPEN = 1  'IPEN: Int Priority Enable bit 'This MUST be included when using Interrupts (Priority HIGH/LOW)[#189 hserin blocking]
PIE1 = %00100000  'RCIE: EUSART Receive Interrupt Enable bit [ 1=en ]
INTCON.PEIE = 1  'PEIE/GIEL: Peripheral Interrupt Enable bit
INTCON.GIE = 1  'GIE/GIEH: Global Interrupt Enable bit *** s

' **** Setup Hw USART ****
Hseropen 9600 

Dim char As Byte
Dim str1(20) As Byte ' *** received message comes to str1
Dim rxi As Byte    ïndex to Str1
Dim msg_rdy As Bit

rxi = 0
msg_rdy = 0
Enable High

Main:
Break  '***stop and put a short msg ending with "!" in to Simulator Rx window

While not msg_rdy // **** the real program can run here and check msg_rdy as needed
Wend

Break  '**** stop, now the Str1 can be looked at the variable window

End                                             

On High Interrupt
Save System

If PIR1.RCIF = 1 Then
  char = RCREG
  str1(rxi) = char
  rxi = rxi + 1
Endif

If char = "!" Then  ' ***  ends the message ****
  msg_rdy = 1
Endif
Resume

Hi J,
And I was looking forward to doing this myself

Thanks very much, I'll put the Aspirin away, much appreciated.

Regarding the 8BIT 16 BIT choice: [ RCSTA.RX9 = 0 '0 = Selects 8-bit reception ] and This routine uses 8BIT, but later there are H and L BYTES, should this be set for 8 or 16BIT?

Regarding the BAUD rate: How do I select [ BAUDCON.BRG16 = 1 '1 = 16-bit Baud Rate Generator – SPBRGH and SPBRG ] ?
Thanks, C.

 

hi,
Read this link.
https://www.microchip.com/forums/m368665.aspx

 

hi,
Read this link.
https://www.microchip.com/forums/m368665.aspx

Hi E,
My question was more to do with setting up UART or PIC.
The UART uses 8BIT, but the MAIN LOOP uses Two's compliment H and L.
As I'm setting up the UART, I assme that I should set that setting to 8BIT, but for the SPI H an L BYTEs they will need 16BIT.
Thanks, C.

 

Hi J,
And I was looking forward to doing this myself

Thanks very much, I'll put the Aspirin away, much appreciated.

Regarding the 8BIT 16 BIT choice: [ RCSTA.RX9 = 0 '0 = Selects 8-bit reception ] and This routine uses 8BIT, but later there are H and L BYTES, should this be set for 8 or 16BIT?

Regarding the BAUD rate: How do I select [ BAUDCON.BRG16 = 1 '1 = 16-bit Baud Rate Generator – SPBRGH and SPBRG ] ?
Thanks, C.

I think Hseropen 9600 takes care of it. It is command for HW Usart

 

I think Hseropen 9600 takes care of it. It is command for HW Usart

Hi J,
Ok, thanks.
C.

 

Hi E,
My question was more to do with setting up UART or PIC.
The UART uses 8BIT, but the MAIN LOOP uses Two's compliment H and L.
As I'm setting up the UART, I assme that I should set that setting to 8BIT, but for the SPI H an L BYTEs they will need 16BIT.
Thanks, C.

Can't you just send 16bit as two 8bit bytes, when you know where they are in the message?

 

Can't you just send 16bit as two 8bit bytes, when you know where they are in the message?

Hi J,
I just checked on one of the peripheral D/S and it appears that one SENDs 3x BYTEs. I'll leave this till later, and leave the UART [ RCSTA.RX9 ] set to 8BIT, for now. thanks.
C.

 

Hi,
Can someone check my homework please?

All SENTENCES start with a $ and end with a W. (Since adding the Barometer altimeter, I don't need the full $NMEA Sentence.)
C.

 

hi,
'While msg_rdy = 0 'the real program can run here and check msg_rdy as needed

When is msg_rdy NOT = 0. ?

E

 

hi,
'While msg_rdy = 0 'the real program can run here and check msg_rdy as needed

When is msg_rdy NOT = 0. ?

E

Hi E,
This is a temporary LOOP, that is broken by the INTERRUPT, and will not be there once the MAIN program comes back.

I haven't checked the actual timing, but just watching the SIM, I'm surprised by the time the processor has to go back to the MAIN LOOP in between $ Sentence digits, coming in.

If you're testing with the SIM, here are some sentences:
$GPRMC,123519,A,4807.038,N,01131.000,W,022.4,084.4,230394,003.1,W*6A?

$GPRMC,123519,A,4807.038,N,01131.000,W,W*6A? ['C' = HEX 0X43 DEC 67]
$QEIDEG,123,W [ 'D' = HEX 0X47 DEC 71]

$REMOTE,12,20,50,W [remvolt,remalt,remdist],? [ 'R' = HEX 0X52 DEC 82]
C

 

Hi E,
This is a temporary LOOP, that is broken by the INTERRUPT, and will not be there once the MAIN program comes back.

I haven't checked the actual timing, but just watching the SIM, I'm surprised by the time the processor has to go back to the MAIN LOOP in between $ Sentence digits, coming in.

If you're testing with the SIM, here are some sentences:
$GPRMC,123519,A,4807.038,N,01131.000,W,022.4,084.4,230394,003.1,W*6A?

$GPRMC,123519,A,4807.038,N,01131.000,W,W*6A? 'C' = HEX 0X43 DEC 67

$QEIDEG,123,W 'D' = HEX 0X47 DEC 71

$REMOTE,12,20,50,W [remvolt,remalt,remdist],? 'R' = HEX 0X52 DEC 82
C

In the ISR when at the end of the message set msg_rdy = 1

 

Hi E,
This is a temporary LOOP, that is broken by the INTERRUPT, and will not be there once the MAIN program comes back.

I haven't checked the actual timing, but just watching the SIM, I'm surprised by the time the processor has to go back to the MAIN LOOP in between $ Sentence digits, coming in.

If you're testing with the SIM, here are some sentences:
$GPRMC,123519,A,4807.038,N,01131.000,W,022.4,084.4,230394,003.1,W*6A?

$GPRMC,123519,A,4807.038,N,01131.000,W,W*6A? 'C' = HEX 0X43 DEC 67

$QEIDEG,123,W 'D' = HEX 0X47 DEC 71

$REMOTE,12,20,50,W [remvolt,remalt,remdist],? 'R' = HEX 0X52 DEC 82
C

The simulator is really slow when receiving characters.
A message ~5 charactes took tens of seconds in the original demo.
Real time execution of the ISR is about 40us at 8MHz.

 

In the ISR when at the end of the message set msg_rdy = 1

Hi J,
Ok,
C

 

The simulator is really slow when receiving characters.
A message ~5 charactes took tens of seconds in the original demo.
Real time execution of the ISR is about 40us at 8MHz.

Hi J,
The simulator is really slow when receiving characters.
I know, from the hours, I've sat watching it

A message ~5 charactes took tens of seconds in the original demo.
Real time execution of the ISR is about 40us at 8MHz.
I'm not used to these speeds, so take some comprehending, but my thought was that there appears to be some time in between the $Sentence digits, for the processor to work on the MAIN LOOP, until the next digit.
C

 

hi C,
This is a simple working bit of code, you should be able to add to it.
Every incoming RX char generates an Interrupt.

Run it,
Type in
$1234? or any other String starting with $ and ending with ? [ ==crlf], it should display the full string.
then type in a test string without the starting $, it should print Error.

Do you follow OK.?
E

 

Hi J,
The simulator is really slow when receiving characters.
I know, from the hours, I've sat watching it

A message ~5 charactes took tens of seconds in the original demo.
Real time execution of the ISR is about 40us at 8MHz.
I'm not used to these speeds, so take some comprehending, but my thought was that there appears to be some time in between the $Sentence digits, for the processor to work on the MAIN LOOP, until the next digit.
C

The ISR slows the processor less than 4% at 8MHz. How critical it is to detect fast the end of the message ?