Replace Shiftout with spi

[Pedro Santos]

Hi Ron

Yes, i mean the hardware SPI
Like You say the Shifout work very good but it is slow, i need to send a byte
quickly to a lcd and perhaps with the hardware SPI pin can i have more speed
The controller that i use is PIC 18F452

Have You a sample code to do that, don't forget it must sent the MSBFIRST

Thanks

Regards

Pedro

[Darrel Taylor]

Pedro,

There's a sample SPI program on the meLabs website.

http://www.melabs.com/resources/samples.htm

Look for spimast.bas

HTH,

[Pedro Santos]

Hi

Yes i see the sample on melabs site but don't understand how to sent
with the spi out pin the msbit first, say bit7, bit6, bit5, ... bit0

Thanks for help
Pedro

[Darrel Taylor]

The MSSP always sends data MSB first.
<br>

[Pedro Santos]

Hello Darrel

my board work correct with this instruction
Shiftout sdata , sclk ,MSBFIRST, [var_out]

Do You know the correct SPI setup to use the hardware SPI to do that?

I try with this and have no function
'spi setup
SSPEN VAR SSPCON1.5 'SSP Enable bit
CKP VAR SSPCON1.4 'Clock Polarity Select
SMP VAR SSPSTAT.7 'Data input sample phase
CKE VAR SSPSTAT.6 'Clock Edge Select bit

TRISC = 0

CKP = 0 'clock idle low 'have changed to 1 for testing but no ok
CKE = 0 'transmit on idle to active transition 'have changed to 1 for testing
'but no ok
SSPIF = 0 'clear SPI interrupt
SMP = 0

main:
SSPEN = 1 'enable SPI pins
SSPBUF = var_out 'send array variable
Return

Have a idea how to fix that?

Thank You

Regards

Pedro

[Darrel Taylor]

For MSBFIRST, you have it correct.

CKP = 0
CKE = 0

Which PIC are you using?
What OSC frequency are you using?
What is it sending data to?

Are you connected to the SDO/SCK pins of the pic?
SDO(PIC) to SDI(slave), AND SCK(PIC) to SCK(slave).

Also, in this code...

main:
    SSPEN = 1 'enable SPI pins 
    SSPBUF = var_out 'send array variable
Return

Since no subroutine was called, the program will reset when it gets to the Return.
<br>

[Pedro Santos]

Hi DarreL

Thanks for Your help
Here is a short code that work in the shiftout version, can you see why the
spi variant not work, i never used spi before.

The pic is 18F452 and the osc is 16Mhz
The data i sent to a little TFT display and with the Shiftout it works fine but a little slow

"Are you connected to the SDO/SCK pins of the pic?
SDO(PIC) to SDI(slave), AND SCK(PIC) to SCK(slave)."

Yes
Lcd_port var PORTC 'Using Port C in the program with the command

Rs var lcd_port.1
Cs var lcd_port.2

Sdata var Lcd_port.5 'spi out pin
Sclk var Lcd_port.3 'spi clk pin

DEFINE OSC 16
TRISC = 0
contrast var byte
lcd_out var byte
contrast = 1

'spi setup
SSPEN VAR SSPCON1.5 'SSP Enable bit
CKP VAR SSPCON1.4 'Clock Polarity Select
SMP VAR SSPSTAT.7 'Data input sample phase
CKE VAR SSPSTAT.6 'Clock Edge Select bit
SSPIF VAR PIR1.3 'interrupt flag - last bit set

CKP = 0 'clock idle low
CKE = 0 'transmit on idle to active transition
SSPIF = 0 'clear SPI interrupt
SMP = 0


main:
gosub adj_contrast
contrast = contrast + 1
pause 1000
goto main


adj_contrast:
Command = 0 'command
Lcd_out = $25 'comand contrast setting
Gosub Lcd_sendbyte
Command = 1 'Parameter
Lcd_out = contrast '..adjust contrast from 0...127
Gosub Lcd_sendbyte
return

Lcd_sendbyte:
SSPEN = 0 'desable SPI pins
cs = 0 'Cs = 0 to start of sequence
sclk = 0 'Clock line to 0
sdata = 1 '1 = parameter
If Command = 0 Then
sdata = 0 '0 = cmd
Endif
sclk = 1
'9 bit ' set it manual to indicate if the next byte is command or parameter
'----------------------------------------------------------------------
SSPEN = 1 'enable SPI pins
SSPBUF = lcd_out 'send variable

''''' Shiftout sdata , sclk ,MSBFIRST, [Lcd_out]' 'send bit after bit of the
'value of variable "Output"
cs = 1 'Cs to 1 at end of sequence
Return



Best regards

Pedro