Serial Baudrate 115200

[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.

[amgen]

are you using a USB to serial converter ?

[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?

[amgen]

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

I don't like to yell because I'm usually wrong.

Just a few thoughts, the Max232 chip inverts signal, if your using USB to serial adapter, that takes a non-inverted signal, so you may be inverting redundently. Also, have you tried OSC-Tune to adjust clock to good 115Kb, then you can use standard Xtal ?

Don

[flotulopex]

Yes, I do use a USB-to-serial interface (FTDI).

I now corrected the BAUDCTL register so as it sends data inverted (no need for a hw inverter anymore).

As far as I understand this register's function, OSCTUNE calibrates the internal oscillator so I don't think it will affect the baud rate generator (I don't know).

BTW, how do I measure a "good" 115200bps signal?

' 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 = 24 'Transmit INVERTED data to RB7, 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

[Charles Linquis]

The baud rate generator will be accurate. If the formula says you will get 115KBaud with a 20Mhz oscillator, you will.
If you don't get 115K baud, then you aren't really running at 20Mhz, or the receiving device has an issue.

I mentioned in another post how to measure just how fast your chip is running - without an oscilloscope.

(Turn LED ON)
For X = 1 to 60
Pause 60000
Next X
(Turn LED OFF)

Wait one hour. If your LED goes off in exactly 60 minutes, your chip is running the speed you think it is. Using a
calculator, you can measure the actual frequency to about 0.1%

A useful tool is BRAY's TERMINAL program (Google it). Free, and it lets you set odd baud rates, like 113Kbaud.
or 120Kbaud.

[flotulopex]

I need to use a 18,432MHz crystal...
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?

Can anyone give some info about this please?

[flotulopex]

I need to use a 18,432MHz crystal...
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?

Does really nobody know something about that?

[Charles Linquis]

You are going to have to unless you change the libraries. Just remember that any PAUSE commands will be 8.5% longer than you think.
You can get around that by creating some variables.

For example: If your program needed 3 different delays 20ms, 50ms, 190ms
You would create 3 vars

delay20 con 18
delay50 con 46
delay190 con 175

Now, if you need a 20mSec delay, you can use the command

PAUSE delay20

It is not exact, but it is close.