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Bit-bang SPI

2007-05-30 by Brian Gregory

Can anyone point me to a bit-bang SPI example? I'm trying to talk to one of
these:
http://www.parallax.com/detail.asp?product_id=29123

Perhaps someone has an equivalent to SHIFTOUT and SHIFTIN in C?

Thanks,
Brian Gregory

Re: [AVR-Chat] Bit-bang SPI

2007-05-31 by David VanHorn

On 5/30/07, Brian Gregory <bgregory@g-webdesign.com> wrote:
> Can anyone point me to a bit-bang SPI example? I'm trying to talk to one of
> these:
> http://www.parallax.com/detail.asp?product_id=29123
>
> Perhaps someone has an equivalent to SHIFTOUT and SHIFTIN in C?
>

Haven't done it in C, but I've had a lot of success in ASM.
It's pretty easy.  I've done multiple devices, one on the hardware SPI
at high speed, while talking to another one at lower speed in bit-bang
mode.

Re: [AVR-Chat] Bit-bang SPI

2007-05-31 by Leon

----- Original Message -----

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From: "Brian Gregory" <bgregory@g-webdesign.com>
To: <AVR-Chat@yahoogroups.com>
Sent: Wednesday, May 30, 2007 9:36 PM
Subject: [AVR-Chat] Bit-bang SPI


> Can anyone point me to a bit-bang SPI example? I'm trying to talk to one 
> of
> these:
> http://www.parallax.com/detail.asp?product_id=29123
>
> Perhaps someone has an equivalent to SHIFTOUT and SHIFTIN in C?
>

Atmel has an app note with code.

Leon
--
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Re: Bit-bang SPI

2007-05-31 by briangregory82

Wow! Thanks for everyone's help.

Brian

Re: [AVR-Chat] Bit-bang SPI

2007-05-31 by Ralph Hilton

On Wed, 30 May 2007 16:36:56 -0400 you wrote:

>Can anyone point me to a bit-bang SPI example? I'm trying to talk to one of
>these:
>http://www.parallax.com/detail.asp?product_id=29123
>
>Perhaps someone has an equivalent to SHIFTOUT and SHIFTIN in C?
>
>Thanks,
>Brian Gregory

Here's code for bit banging an ADC chip showing how a shift in and out can be
done:

#define LTCSDI PORTD.2  
#define LTCCS PORTD.3
#define LTCSDO PIND.4
#define LTCSCK PORTD.5

char i;
bit inbit;
bit msb;
bit datasign;
bit adcflag; 
flash char LTCspeeds[10]={16,8,24,4,20,12,28,2,18,30};  //stored in reverse
order for easy out with >>
char speed=3, speedout;
char outbyte1, outbyte2, outbyte3, outbyte4;
unsigned long int rawdataval, mcdataval;
unsigned long int lastmcdataval; 

void readbit(void)
{     
LTCSCK=1;   
delay_us(2);
inbit=LTCSDO;
delay_us(2);
LTCSCK=0;   
}

void setsdi(void)
{
LTCSDI=speedout&1;   
speedout>>=1;
}

void main(void)
{
sleep_enable(); 
LTCCS=1; //start conversion
idle(); //take a nap until timer 0 interrupt
while (1)
{
if (adcflag)
{      
    
    speedout=LTCspeeds[speed];
    rawdataval=0; 
    LTCCS=0;
    while (LTCSDO==1);
    setsdi();
    readbit(); //EOC   
    setsdi();
    readbit(); //dummy
    setsdi();
    readbit(); //sign
    datasign=inbit;
    setsdi();
    readbit(); //msb
    msb=inbit;
    setsdi();
    for (i=0;i<23;i++)
    { 
       readbit();
       rawdataval<<=1;
       rawdataval+=inbit;
    }
    LTCCS=1; //start next conversion 
--
Ralph Hilton
http://www.ralphhilton.org
C-Meter: http://www.cmeter.org
FZAOINT http://www.fzaoint.net

Re: [AVR-Chat] Bit-bang SPI

2007-05-31 by BobGardner@aol.com

> Can anyone point me to a bit-bang SPI example? 

=============================================
#define DATHI() PORTB |= 0x01;
#define DATLO() PORTB &= ~0x01;
#define CLKHI() PORTB |= 0x02;
#define CLKLO() PORTB &= ~0x02;

void bb(char n){
unsigned char msk;

  msk=0x80;
  while(msk){
    if(msk & n) DATHI(); else DATLO();
    CLKHI();
    CLKLO();
    msk >>=1;
  }
}





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Re: [AVR-Chat] Bit-bang SPI, I have a code!

2007-06-01 by maria mastik

Hi
  I have done such thing before.
  My code is like bellow
  the function "Source_transmit()" transsends 4 bytes in each call.
   
  Mohammad.
   
  code -->
   
   
  #define source_SCK   PORTC.2
#define source_MOSI  PORTC.4
#define source_MISO  PINC.3
#define source_RST   PORTC.5
  
//========================================================================
  unsigned char inbyte[4],outbyte[4],i;
  //========================================================================
  
void source_transmit(void)
{
source_SCK=0;
inbyte[0]=inbyte[1]=inbyte[2]=inbyte[3]=0;
 
for(i=0;i<4;i++)
 {
 source_MOSI=(outbyte[i] & 0b10000000);delay_us
  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
  ++;source_SCK=0;
 source_MOSI=(outbyte[i] & 0b01000000);delay_us
  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
  ++;source_SCK=0;
 source_MOSI=(outbyte[i] & 0b00100000);delay_us
  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
  ++;source_SCK=0;
 source_MOSI=(outbyte[i] & 0b00010000);delay_us
  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
  ++;source_SCK=0;
 source_MOSI=(outbyte[i] & 0b00001000);delay_us
  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
  ++;source_SCK=0;
 source_MOSI=(outbyte[i] & 0b00000100);delay_us
  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
  ++;source_SCK=0;
 source_MOSI=(outbyte[i] & 0b00000010);delay_us
  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
  ++;source_SCK=0;
 source_MOSI=(outbyte[i] & 0b00000001);delay_us
  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
  ++;source_SCK=0;
      }
}
//===================================================================
  void main(void)
{
unsigned char temp[2],a,b;
  // Crystal Oscillator division factor: 1
CLKPR=0x80;
CLKPR=0x00;
  // Input/Output Ports initialization
PORTB=0b00111100;DDRB=0b00000011;
PORTC=0b01001000;DDRC=0b00110100;
PORTD=0b00000010;DDRD=0b11101101;
  ACSR=0x80;ADCSRB=0x00;
  while (1)
      {
 
 outbyte[0]=12;outbyte[1]=98;outbyte[2]=5;outbyte[3]=34;
 source_transmit();
 
 temp1=inbyte[0];
 temp2=inbyte[1];
 a=inbyte[2];
 b=inbyte[3];
      };
}


David VanHorn <microbrix@gmail.com> wrote:
          On 5/30/07, Brian Gregory <bgregory@g-webdesign.com> wrote:
> Can anyone point me to a bit-bang SPI example? I'm trying to talk to one of
> these:
> http://www.parallax.com/detail.asp?product_id=29123
>
> Perhaps someone has an equivalent to SHIFTOUT and SHIFTIN in C?
>

Haven't done it in C, but I've had a lot of success in ASM.
It's pretty easy. I've done multiple devices, one on the hardware SPI
at high speed, while talking to another one at lower speed in bit-bang
mode.


         

       
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Re: [AVR-Chat] Bit-bang SPI, I have a code!

2007-06-01 by Ralph Hilton

On Fri, 1 Jun 2007 08:31:28 -0700 (PDT) you wrote:

>Hi
>  I have done such thing before.
>  My code is like bellow
>  the function "Source_transmit()" transsends 4 bytes in each call.
>   
>  Mohammad.

I'm glad I'm not responsible for maintaining that code! Try some spacing,
separate lines for separate statements and liberal use of comments.

Compact code might look clever but think of the guy who has to figure out what
it does!
 
>  code -->
>   
>   
>  #define source_SCK   PORTC.2
>#define source_MOSI  PORTC.4
>#define source_MISO  PINC.3
>#define source_RST   PORTC.5
>  
>//========================================================================
>  unsigned char inbyte[4],outbyte[4],i;
>  //========================================================================
>  
>void source_transmit(void)
>{
>source_SCK=0;
>inbyte[0]=inbyte[1]=inbyte[2]=inbyte[3]=0;
> 
>for(i=0;i<4;i++)
> {
> source_MOSI=(outbyte[i] & 0b10000000);delay_us
>  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
>  ++;source_SCK=0;
> source_MOSI=(outbyte[i] & 0b01000000);delay_us
>  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
>  ++;source_SCK=0;
> source_MOSI=(outbyte[i] & 0b00100000);delay_us
>  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
>  ++;source_SCK=0;
> source_MOSI=(outbyte[i] & 0b00010000);delay_us
>  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
>  ++;source_SCK=0;
> source_MOSI=(outbyte[i] & 0b00001000);delay_us
>  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
>  ++;source_SCK=0;
> source_MOSI=(outbyte[i] & 0b00000100);delay_us
>  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
>  ++;source_SCK=0;
> source_MOSI=(outbyte[i] & 0b00000010);delay_us
>  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
>  ++;source_SCK=0;
> source_MOSI=(outbyte[i] & 0b00000001);delay_us
>  (10);source_SCK=1;delay_us(10);inbyte[i]<<=1;if (source_MISO) inbyte[i]
>  ++;source_SCK=0;
>      }
>}
>//===================================================================
>  void main(void)
>{
>unsigned char temp[2],a,b;
>  // Crystal Oscillator division factor: 1
>CLKPR=0x80;
>CLKPR=0x00;
>  // Input/Output Ports initialization
>PORTB=0b00111100;DDRB=0b00000011;
>PORTC=0b01001000;DDRC=0b00110100;
>PORTD=0b00000010;DDRD=0b11101101;
>  ACSR=0x80;ADCSRB=0x00;
>  while (1)
>      {
> 
> outbyte[0]=12;outbyte[1]=98;outbyte[2]=5;outbyte[3]=34;
> source_transmit();
> 
> temp1=inbyte[0];
> temp2=inbyte[1];
> a=inbyte[2];
> b=inbyte[3];
>      };
>}

--
Ralph Hilton
http://www.ralphhilton.org
C-Meter: http://www.cmeter.org
FZAOINT http://www.fzaoint.net