MSP430G2955 SPI communication

Aashna Mittal

Hi!

I am trying to communicate between two MSP430G2955 using the SPI(Master/slave) protocol. Currently, I am using the example codes provided in the resource explorer. However, I am not able to see any data on the logic analyzer. I tried different combinations for UCCKPL and UCCKPH, but still no success. Could someone point out the possible errors.

The hardware connections are as follows:

MASTER SLAVE
MOSI--->MISO

MISO--->MOSI

CLOCK out-->CLOCK in

Chip select-->RST/NMI

Any leads would be appreciated.

Thanks

over 11 years ago

0 eltury over 11 years ago

Genius 3330 points

Is your chip select holding the slave in RESET?

0 Aashna Mittal over 11 years ago in reply to eltury

Prodigy 135 points

Yes, it is.

0 Jens-Michael Gross over 11 years ago

Guru 227245 points

It's a bad idea ‘slecting’ a slave through its RST pin (even though it has been done in an 'official' demo code too)

Once ‘selected’, the slave needs to boot up, which can take a significant time which is unknown to the master. So the master needs some feedback form the slave whethe rht eslave is doen booting and reay for operation.

Better control the slave reset by a transfer-independent I/O (or not at all), and check the CS signal on the running slave (e.g. with a port pin IRQ).

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MSP430G2955 SPI communication