[Solved]DPSI MOSI problem

[270284440]

Posted on February 10, 2015 at 08:33

when I use DSPI , I send two frames 16bits per frame, and I monitor that there is a pulse inter frame on MOSI pin (suppose I send two frames  0x00000000 ), it is very strange , I checked step and step,when I set MOSI pin as SIU.PCR[38].R=0x0604 or 0x06xx; MOSI will change to high value;

So I guess the interframe high level shown is due to MOSI return to default value high.

But can I set default value of MOSI as low level value ?

--Note , there is no external pull up on MOSI , and when I configure MOSI as output low , the pin still show highlevel.

[disirio2]

Posted on February 10, 2015 at 18:58

Hi,

It is possible it is just an issue with the tDT delay time, see the Reference Manual. You need to program the PDT, PASC, PCSSCK fields of the CTAR register(s) in order to program the inter-frame time. Note that all the fields in the CTAR register are quite important and must be programmed correctly or you will get strange results.

Giovanni

[270284440]

Posted on February 11, 2015 at 02:37

Thank you for your quick reply, I understand the point you mentioned, another point is Can MOSI pin set to low level in idle(No data communication) time ?

[disirio2]

Posted on February 11, 2015 at 13:36

HI,

MOSI cannot be directly controlled, its idle state is always high. You could switch it to GPIO and control it ''manually'' but are you sure it is really required?

Giovanni

[270284440]

Posted on February 12, 2015 at 02:33

Hi, Giovanni

'' its idle state is always high'' -- this is the point I need to confirm, thank you so much!