hello all
i'm facing problem in Implementing SPI daisy chain for AD5293 digital pot, the connection as shown in bellow fig.
here i want to shift my data until to 48 clock cycle with respect i need to make DSPI1_CS0_BAR pin should be low until 48 clock cycle to read/write DPOT data. Is it possible to make DSPI1_CS0_BAR pin low for 48 cycle. if yes how can i make it low for 48 clock cycle.
Hello Petr,
SCK is not the problem here. We need to keep the Chip Select low for 3 x 16 Data out transfers. But i observe is that the chip select goes high and then goes low after each 16 bit transfers, and this is the problem. When we put the first 16bit data into the push register and check for transfer complete flag and once it is transmitted then we push the second 16bit data but here the chip select goes high which is undesired. Below is the snapshot of the data sheet of AD5293. In our application we are using 3 AD5293 in daisy chain configuration. We configured clock to be continuous with CPOL = 0, CPHA =1 and 32Mhz dspi pheripheral clock.
Kindly let us know how can we control the Chip Select Line for 48 bit data transfer.
I did not understand this below diagram in the manual. Does the CS goes high after 1 transfer?
Regards,
Ningu
Hello,
Thanks for the information.
After much debugging we were able to resolve most of the things except one, that is when we write into the digital pot 3 and after read back it always reads as zero.
Data written into Digital Pot 1 and Digital Pot 2 were able to successful read whatever we have written.
Sequence :
Write to Digital Pot1 with PUSH Contents : 0x8001XXXX
Write to Digital Pot2 with PUSH Contents : 0x8001XXXX
Write to Digital Pot3 with PUSH Contents : 0x0001XXXX
POT 3 Read
Then we do a dummy PUSH with 0x0001XXXX command to get the POP contents of Digital Pot3
POT2 Read
Then we do a dummy PUSH with 0x8001XXXX command.
Then we do a dummy PUSH with 0x0001XXXX command to get the POP contents of Digital Pot2
POT1 Read
Then we do a dummy PUSH with 0x8001XXXX command.
Then we do a dummy PUSH with 0x8001XXXX command.
Then we do a dummy PUSH with 0x0001XXXX command to get the POP contents of Digital Pot1
When we do this the POP contents of Digital Pot 1 is always zero or missed.
We verified the contents of the SPI registers and it all looks good on the transmission.
Please give us hint where to look in to resolve this behaviour. Any advice on debugging this issue would be great help.
Any design advice is for such daisy chain configuration is also appreciated.
we followed bellow design:
Kindly check the configuration below.
Below is my DSPI_0 configuration :
/*..................Testing.......................*/
void initModesAndClks(void)
{
ME.MER.R = 0x0000001D; /* Enable DRUN, RUN0, SAFE, RESET modes */
/* Initialize PLL before turning it on: */
CGM.FMPLL_CR.R = 0x02400100; /* 8 MHz xtal: Set PLL0 to 64 MHz */
ME.RUN[0].R = 0x001F0074; /* RUN0 cfg: 16MHzIRCON,OSC0ON,PLL0ON,syclk=PLL */
ME.RUNPC[1].R = 0x00000010; /* Peri. Cfg. 1 settings: only run in RUN0 mode */
ME.PCTL[4].R = 0x01; /* MPC56xxB/P/S DSPI0: select ME.RUNPC[1] */
ME.PCTL[5].R = 0x01; /* MPC56xxB/P/S DSPI1: select ME.RUNPC[1] */
ME.PCTL[68].R = 0x01; /* MPC56xxB/S SIUL: select ME.RUNPC[0] */
/* Mode Transition to enter RUN0 mode: */
ME.MCTL.R = 0x40005AF0; /* Enter RUN0 Mode & Key */
ME.MCTL.R = 0x4000A50F; /* Enter RUN0 Mode & Inverted Key */
while (ME.GS.B.MTRANS) {} /* Wait for mode transition to complete */
/* Note: could wait here using timer and/or I_TC IRQ */
while(ME.GS.B.CURRENTMODE != 4) {} /* Verify RUN0 is the current mode */
}
void initPeriClkGen(void)
{
/* Use the following code as required for MPC56xxB or MPC56xxS:*/
CGM.SC_DC[1].R = 0x81; ; /* MPC56xxB/S: Enable peri set 2 sysclk divided by 1 */
}
void disableWatchdog(void)
{
SWT.SR.R = 0x0000c520; /* Write keys to clear soft lock bit */
SWT.SR.R = 0x0000d928;
SWT.CR.R = 0x8000010A; /* Clear watchdog enable (WEN) */
}
void initDSPI_0(void)
{
DSPI_0.MCR.R = 0x80010001; /* Configure DSPI_0 as master */
DSPI_0.CTAR[0].R = 0x7A0A7727; /* Configure CTAR0 */
DSPI_0.MCR.B.HALT = 0x0; /* Exit HALT mode: go from STOPPED to RUNNING state*/
SIU.PCR[13].R = 0x0604; /* MPC56xxB: Config pad as DSPI_0 SOUT output */
SIU.PCR[12].R = 0x0103; /* MPC56xxB: Config pad as DSPI_0 SIN input */
SIU.PCR[14].R = 0x0604; /* MPC56xxB: Config pad as DSPI_0 SCK output */
SIU.PCR[15].R = 0x0604; /* MPC56xxB: Config pad as DSPI_0 PCS0 output */
}
void initDSPI_1(void)
{
DSPI_1.MCR.R = 0x00010001; /* Configure DSPI_1 as slave */
DSPI_1.CTAR[0].R = 0x780A7727; /* Configure CTAR0 */
DSPI_1.MCR.B.HALT = 0x0; /* Exit HALT mode: go from STOPPED to RUNNING state*/
SIU.PCR[68].R = 0x0903; /* MPC56xxB: Config pad as DSPI_1 SCK input */
SIU.PSMI[7].R = 1; /* MPC56xxB: Select PCR 68 for DSPI_1 SCK input */
SIU.PCR[36].R = 0x0103; /* MPC56xxB: Config pad as DSPI_1 SIN input */
SIU.PSMI[8].R = 0; /* MPC56xxB: Select PCR 8 for DSPI_1 SIN input */
SIU.PCR[37].R = 0x0604; /* MPC56xxB: Config pad as DSPI_1 SOUT output*/
SIU.PCR[69].R = 0x0903; /* MPC56xxB: Config pad as DSPI_1 PCS0/SS input */
SIU.PSMI[9].R = 2; /* MPC56xxB: Selec PCR 15 for DSPI_1 SS input */
}
Let me know if you need some detailed information we can provide a diagram for better explanation of the issue.
Regards,
Raghavendra P
