Serial Baudrate 115200

[flotulopex]

I'm having difficulties making my PIC's HSEROUT working at all. I need to get 115200bps.

I can reach 38400bps with the SEROUT2 command without any trouble.

For 115200bps, I go with HSEROUT. I use the MCS Serial Communicator and the PIC has a 20MHz crystal.

SEROUT2 is okay, HSEROUT is not working at all (not even @1200bps).

I've been trying to make it work for hours and hours, redoing the cabling (see picture) different ways as suggested in other threads, modifying the code also many times but no success until now. I just always get garbage on the serial terminal's screen.

' SEROUT2
  
' PIC 16F690 Fuses
@ __Config _FCMEN_OFF &_IESO_OFF &_BOR_OFF &_CPD_OFF &_CP_OFF &_MCLRE_OFF &_PWRTE_OFF &_WDT_OFF &_HS_OSC
 
OPTION_REG = 000000 'PORT A&B Pull-Ups (look WPUA & WPUB)
ADCON0     = 000000 'A/D Module
ANSEL      = 000000 'Select analog inputs Channels 0 to 7
ANSELH     = 000000 'Select analog inputs Channels 8 to 11
INTCON     = 000000 'INTERRUPT Control
'WPUA       = 000000 'Select PORTA weak pull-ups
'IOCA       = 000000 'Interrupt On Change selection
CM1CON0    = 000000 'Comparator1 Module
CM2CON0    = 000000 'Comparator2 Module
TRISA      = 000000 'Set Input/Output (0 to 5)
PORTA      = 000000 'Ports High/Low (0 to 5)
TRISB      = 000000 'Set Input/Output (4 to 7)
PORTB      = 000000 'Ports High/Low (4 to 7)
TRISC      = 000000 'Set Input/Output (0 to 7)
PORTC      = 000000 'Ports High/Low (0 to 7)
 
'-------------------------------------------------------------------------------
' DEFINEs
DEFINE OSC 20
DEFINE LCD_COMMANDUS 2000
DEFINE LCD_DATAUS 50
 
'-------------------------------------------------------------------------------
LED1    VAR PORTA.2
Counter VAR WORD
Counter = 0
 
TEST:
  TOGGLE LED1
  'serout2 PORTB.7,16416,[dec counter,13,10]'19200 DIN with MAX232
  SEROUT2 PORTB.7,16390,[DEC Counter,13,10]'38400 DIN with MAX232
  PAUSE 500
  Counter = Counter + 1
  GOTO TEST
  
  END

' HSEROUT
  
' PIC 16F690 Fuses
@ __Config _FCMEN_OFF &_IESO_OFF &_BOR_OFF &_CPD_OFF &_CP_OFF &_MCLRE_OFF &_PWRTE_OFF &_WDT_OFF &_HS_OSC
 
OPTION_REG = 000000 'PORT A&B Pull-Ups (look WPUA & WPUB)
ADCON0     = 000000 'A/D Module
ANSEL      = 000000 'Select analog inputs Channels 0 to 7
ANSELH     = 000000 'Select analog inputs Channels 8 to 11
INTCON     = 000000 'INTERRUPT Control
'WPUA       = 000000 'Select PORTA weak pull-ups
'IOCA       = 000000 'Interrupt On Change selection
CM1CON0    = 000000 'Comparator1 Module
CM2CON0    = 000000 'Comparator2 Module
TRISA      = 000000 'Set Input/Output (0 to 5)
PORTA      = 000000 'Ports High/Low (0 to 5)
TRISB      = 000000 'Set Input/Output (4 to 7)
PORTB      = 000000 'Ports High/Low (4 to 7)
TRISC      = 000000 'Set Input/Output (0 to 7)
PORTC      = 000000 'Ports High/Low (0 to 7)
 
'-------------------------------------------------------------------------------
' DEFINEs
DEFINE OSC 20
DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 24h
DEFINE HSER_BAUD 19200
'DEFINE HSER_SPBRG 64
DEFINE HSER_CLOERR 1
 
'-------------------------------------------------------------------------------
LED1    VAR PORTA.2
Counter VAR WORD
Counter = 0
 
TEST:
  TOGGLE LED1
  HSEROUT [DEC Counter,13,10]
  PAUSE 500
  Counter = Counter + 1
  GOTO TEST
  
  END  

There's a MAX232 close to the PIC making me think the lines are as short as possible. But is it enough on the hw side?

[Charles Linquis]

Try changing

DEFINE HSER_TXSTA 24h to

DEFINE HSER_TXSTA 20h

[flotulopex]

I tried this already: no success.

Still looks like this:

[Charles Linquis]

I was referring to you trying to run 19200. That was what your code above referenced.

If you want to run 115K baud -

From Mr. E's Multi-Calc:

RCSTA1 = $90 ' Enable serial port & continuous receive
TXSTA1 = $24 ' Enable transmit, BRGH = 1
SPBRG1 = 42 ' 115200 Baud @ 20MHz, 0.94%
SPBRGH1 = 0
BAUDCON1.3 = 1 ' Enable 16 bit baudrate generator

Some of these might change if you are using a 16F part.

You may have to remove the "1" after the register names if you are not using PBP 3

[amgen]

if serout2 was inverted, HSER is not inverted. 16416 in table shows inverted.

[dhouston]

Is there any way to set the DEBUG baud rate at runtime?

[flotulopex]

if serout2 was inverted, HSER is not inverted. 16416 in table shows inverted.

Sorry, I don't understand what you want me to do?! I don't have any problems with SEROUT2 at this time.

I was referring to you trying to run 19200...

I did try this at all available baudrates; never worked. Before you ask, yes, I tried with another PIC

I do use a PIC16F690 and modified the code with your suggestion as it is herunder:

' HSEROUT

' PIC 16F690 Fuses
@ __Config _FCMEN_OFF &_IESO_OFF &_BOR_OFF &_CPD_OFF &_CP_OFF &_MCLRE_OFF &_PWRTE_OFF &_WDT_OFF &_HS_OSC

OPTION_REG = %10000000 'PORT A&B Pull-Ups (look WPUA & WPUB)
ADCON0     = %00000000 'A/D Module
ANSEL      = %00000000 'Select analog inputs Channels 0 to 7
ANSELH     = %00000000 'Select analog inputs Channels 8 to 11
INTCON     = %00000000 'INTERRUPT Control
'WPUA       = %00000000 'Select PORTA weak pull-ups
'IOCA       = %00000000 'Interrupt On Change selection
CM1CON0    = %00000000 'Comparator1 Module
CM2CON0    = %00000000 'Comparator2 Module
TRISA      = %00000000 'Set Input/Output (0 to 5)
PORTA      = %00000000 'Ports High/Low (0 to 5)
TRISB      = %00000000 'Set Input/Output (4 to 7)
PORTB      = %00000000 'Ports High/Low (4 to 7)
TRISC      = %00000000 'Set Input/Output (0 to 7)
PORTC      = %00000000 'Ports High/Low (0 to 7)

'-------------------------------------------------------------------------------
' DEFINEs
DEFINE OSC 20
RCSTA = $90 ' Enable serial port & continuous receive
TXSTA = $24 ' Enable transmit, BRGH = 1
SPBRG = 42 ' 115200 Baud @ 20MHz, 0.94%
BAUDCTL.3 = 1 'for PIC16F690 - BAUDCON1.3 = 1 ' Enable 16 bit baudrate generator 

'-------------------------------------------------------------------------------
LED1    var PORTA.2
Counter var word
Counter = 0

TEST:
  Toggle led1
  HSEROUT [dec counter,13,10]
  pause 500
  Counter = counter + 1
  goto test
  
  end

As said, I tried also the lowest selectable baudrate 300bps; even so, I can't see any "good" data in the terminal.

[mister_e]

back to basic Roger... check your ANSEL(h) settings.. you're sending something on a analog configured pin.

[flotulopex]

if serout2 was inverted, HSER is not inverted.

Why didn't you SHOUT IT OUT LOUD!!??

You're absolutely right: the signal has to be inverted in the way I'm using it. I added a transistor to invert the signal going to the MAX232 chip and guess what: IT WORKS!!!!

The HSEROUT code example in one of my previous post is working fine, also with 115200bps.

I still have some transmission errors but I think this can be due to the small error rate - I'll try with a 18,432MHz crystal.

Thanks a lot and have a nice day.

[flotulopex]

Hi there,

I need to use a 18,432MHz crystal with this PIC16F690 project to achieve a clean 115200bps serial comm.

Looking at the OSC values in the DEFINEs list, I can't find the value "18".

Shall I simply define the OSC as, i.e., "20" while connecting a 18MHZ crystal?

The only drawback I can see is about timing in PAUSE commands or similar. I assume the HUSART will still run from the 18MHz osc; right?

Any other problems I wouldn't see?