Lpc2000

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http://groups.yahoo.com/group/lpc2000/message/4363

rockraj_2003 wrote:

>
> Hello Mark,
>
> I am using SPI to configure the DP1203.
>
> LPC2106 - FULL DUPLEX.
> DP1203 - HALF DUPLEX.
>
> I just wrote ur program in IAR but when the SSEL is low it's not
> responding.
> There is no SCK.
>
> When SSEL pin is high it's responding correctly.
> I can able to see the Serial Clock and the Data Transmission in the
> MOSI line as well.
> But I can't able to receive any data in the MISO line.
> It's in low state. There is no response.
>
> When i transmit the Tx1 it's giving only "00" for 8 times.
> Here is the simple code.
>
> #include "LPC210x.H"
> #include "ma_uart0.h"
>
> void main (void)
> {
> unsigned char Tx[] = {1,2,3,4,5,6,7,8};
> unsigned char Tx1[8];
>
> unsigned short Length;
>
> unsigned char *ptrData,*Rx;
>
> MA_Init_UART0();
> MA_Reset_UART0();
> Length = sizeof(Tx);
>
> ptrData = Tx;
> VPBDIV = 0;
> Rx = Tx1;
>
> IODIR = 0x80;
> IOSET = 0x80;
> PINSEL0 = 0x5505;
> SPI_SPCCR = 0xFF;
> SPI_SPCR = 0x20;
>
> while (Length--)
> {
>   IOSET = 0x80; // remove SSEL
>   SPI_SPDR = *ptrData++; // Set data Byte
>   while((SPI_SPSR & 0x80)==0);
>   IOCLR = 0x80; // activate SSEL
>   *Rx++ = (unsigned char)SPI_SPDR;
> } 
> for(short i=0;i<=7;i++)
>   {
>     while(U0LSR==0x00){;}
>     U0THR = Tx1[i] ; 
>     }
> }
>
> Kindly Help me to solve the probl.
>
> Is there any other example code that send as well as receive data in
> MOSI & MISO line throu SCK.
>
> with regards,
> Rajendra R
>
>
>
> Hi Rajendra (Mark),
>
> Mark has covered SPI operation very well, that's the nuts and bolts
> of it.
>
> Maybe one last remark to make it sink in a bit easier again.
> Think of SPI as a 16 bit shift register, with a "Master" as 8 bit
> shift
> register,
> and a Slave as an 8 bit shift register, and with a feedback from the
> output of
> bit 15
> into bit 0.
>
> Thus, all that happens is that Master and Slave _exchange_ their 8
> bits when the
> 8 clock pulses are issued. No matter which side (ie. Master or
> Slave), data is
> read
> on one edge of clock pulses, while data is output on the opposite
> edge of the
> clock pulse.
> This means the Master for example can change the "1" or "0" data
> output while
> it's
> reading the data line, since the Slave is NOT sampling MOSI at that
> moment, and
> vice-versa
> for the Slave with MISO.
>
> The only thing that qualifies a Master from a Slave is whom issues
> the clock
> pulses.
> Hence the whole system is synchronous.
> There might even be times where it is handy to "hold" the SPI
> transfer. That
> even can
> be one in HW : Some SPI (SLAVE) devices have a /HOLD input pin.
> (A bit restricting IMO, because you can only change /Hold when
> clock "idle").
>
> Because you can clock data at rising or falling edge - and - you can
> keep your
> clock "Idle"
> High or Low _between_ bit transfers, there are FOUR combinations ::::
> referred to sometimes as SPI Mode 0,1,2 and 3.
>
> Happy trails
> -- Kris
>
> > Hallo Rajendra
> >
> > When the SPI (master) sends 8 bits of data over the MOSI line it
> > also clocks in 8 bits of data via the MISO line. Therefore when a
> > byte of data has successfully been sent (SPI_SPSR & 0x80 becomes
> > true) it also has a byte of received data which can be read from
> > SPI_SPDR. (when no slave it is probably 0xff or 0x00 depending on
> > the line state - if the slave has nothing to send it depends on the
> > device - eg. the LPC210x in slave mode sends byte the last received
> > byte)
> >
> > This means that the slave must prepare and send data - the exact
> > sequence will depend on your peripheral device but it generally
> > means that you must first send a command byte to inform which data
> > it should sent to you and then you can read it (one or a sequence of
> > bytes). If the master has no data to send while reading the byte(s)
> > it can send a dummy byte (0xff or 0x00 etc.).
> >
> > The code to send and also read in full duplex (assuming the slave
> > supports it) could look like this:
> >
> > void fnSendReceive(unsigned char *out, unsigned char *in, unsigned
> > short usLength)
> > {
> > while (usLength--) {
> > IOCLR = SPI_SSEL_OUT; // activate SSEL
> > SPDR = *out; // send data byte
> > while (!(SPSR & SPIF)) {}; // wait for transmission to
> > complete
> > IOSET = SPI_SSEL_OUT; // remove SSEL
> > *in++ = (unsigned char)SPDR; // save data
> > }
> > }
> >
> > Note that the LPC210x has a very simple SPI which has only one
> > interrupt flag to indicate when the transmission has completed and
> > the received data is available. There is no buffering in the
> > transmitter and so it is imperative that the flag is set before
> > sending the next byte otherwise it may be lost - as consequence the
> > throughput tends to suffer since the software processing has to take
> > place almost completely between transmission periods and it is
> > hardly possible to do any work during the byte transmission
> interval.
> >
> > Regards
> >
> > Mark Butcher
> >
> > www.mjbc.ch
> >
> >
> > --- In lpc2000@yahoogroups.com, "rockraj_2003" <rockraj_2003@y...>
> > wrote:
> > >
> > > Hello Mark,
> > >
> > > Thanks for Ur Response.I tried Ur Code its working fine.
> > > I aslo changed my prog.This Code is also giving the Same response.
> > > I didn't CLR the SSEL pin at all.But I regularly changed SPIF to
> > 0x00.
> > >
> > > Now, my doubt is if i want to use MISO as well what should i do.
> > > Since in the Data Sheet THE mentioned SPI as duplex.
> > >
> > > How I can use MISO.
> > >
> > > Silly Question, but I don't know about this.
> > > If the SPI is in MOSI, it can send DATA (MASTER OUTPUT) at the
> > Same
> > > time it receive data in SLAVE.(SLAVE INPUT).How much time it will
> > > wait to receive DATA. If again I put some Data to the SPI_SPDR it
> > > will transmit or it will wait to receive.
> > >
> > > > > #define SPI_SPCR (*((volatile unsigned char *)
> > 0xE0020000))
> > > > > #define SPI_SPSR (*((volatile unsigned char *)
> > 0xE0020004))
> > > > > #define SPI_SPDR (*((volatile unsigned char *)
> > 0xE0020008))
> > > > > #define SPI_SPCCR (*((volatile unsigned char *)
> > 0xE002000C))
> > > > > #define SPI_SPTCR (*((volatile unsigned char *)
> > 0xE0020010))
> > > > > #define SPI_SPTSR (*((volatile unsigned char *)
> > 0xE0020014))
> > > > > #define SPI_SPTOR (*((volatile unsigned char *)
> > 0xE0020018))
> > > > > #define SPI_SPINT (*((volatile unsigned char *)
> > 0xE002001C))
> > > > >
> > > > > int main (void)
> > > > > {
> > > > > int i;
> > > > > VPBDIV = 1;
> > > > > IODIR = 0x80;
> > > > > IOSET = 0x80;
> > > > > PINSEL0 = 0x5500;
> > > > > SPI_SPCCR = 0x93;
> > > > > SPI_SPCR = 0x20;
> > > > > while (1) {
> > > > > do SPI_SPDR = 0x55;
> > > > > while((SPI_SPSR & 0x80)==0);
> > > > > SPI_SPSR = 0x00;
> > > > > do SPI_SPDR = 0x0F;
> > > > > while((SPI_SPSR & 0x80)==0);
> > > > > SPI_SPSR = 0x00;
> > > > > do SPI_SPDR = 0xF0;
> > > > > while((SPI_SPSR & 0x80)==0);
> > > > > SPI_SPSR = 0x00;
> > > > > }
> > > > > }
> > >
> > >
> > > with Regards
> > > Rajendra R
> > >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
>
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