Hi,
I want to use DSPI0 on the MPC5746 to communicate with FS65xx SBC chip. I found an example for such communication, using MPC5744P (project attached for easy reference) and ported it to MPC5746, I scoped the all four SPI lines(MISO/MOSI/CLK/CS) but I do not see any activity on the data and clock line. At least the clock should toggle. CS goes low, so I know I am looking at the right interface.
I have several questions regarding the clock configuration and baud rate settings and any limits:
1. On the MPC5746, there are two derived clocks in the clock tree - DSPI0 and DSPI1, which can be configured to two separate frequencies. But the MPC has more than 2 SPI interface.
How do i know which SPI interface is using which of these two clocks?
2. Given the following, how do I arrive at the register fields for CTAR?
system clock = 150MHz;
DSPI_CLK0 is 75MHz and & DSPI_CLK1 is 50MHz ( these can be changed.)
FrameSize: 16bits
SPI Clock Frequency: 8MHz
SPI Baud Rate : 1M
The clock generation is different between the MPC5744 and MPC5746 (on MPC5744 , the pre-scaler value is configured via the CTAR configuration fields, while on the MPC5746R the prescaling is done using the divider for the AUXCLK).
I used the function provided in the MPC5744P example's DSPI driver,
void DSPI_Init(uint8_t DspiNumber,uint8_t mode, uint32_t sysClk, uint32_t baudRate, uint32_t intMask)
and use my DSPI_CLK0 for sysclk in the above, but cannot see any activity on SPI bus.
3. In the SBC example, DSPI configuration I see a comment:
Maximal and minimal Baud rate depends on * the actual system clock frequency and on the limits of the PBR and * BR registers. Maximal and minimal values for fsys = 16 MHz are shown * in the table below, for other frequencies see the external excel file.Where can I find the excel file with the limits for PBR and BR?
Thank you for taking time to respond.
