Using SPI mode to interface msp430 with RF transciever and SD card

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The discussion focuses on interfacing an eZ430-RF2500, which includes an MSP430 microcontroller and a CC2500 RF transceiver, with a Sandisk SD card using SPI mode. The main concern is whether the same SPI pins (SOMI, SIMO, SCK, STE) can be used for both the RF transceiver and the SD card, with the MSP430 acting as the master. While it's suggested that the STE pin can be utilized for slave selection, caution is advised as connecting both devices could lead to data conflicts if not managed properly. A not gate can be used to control the chip select for the SD card, but it is recommended to use a separate line for better reliability. Proper slave selection is crucial to avoid unintended data reception from the SD card when the RF transceiver is not selected.
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Hi,

I am planning to use SPI mode to interface a eZ430-RF2500 with a Sandisk Secure Digital Card. The eZ430-RF2500 includes a MSP430 microcontroller and a CC2500 RF transceiver. According to the schematic, the RF transceiver interfaces the MSP430 utilizing the SPI mode, using the SOMI, SIMO, SCK, STE(for chip selecting) pins of MSP430.

The problem is can I connect the MSP430 with SD card using the same set of input wires(SOMI, SIMO, SCK, STE)? In this case, I suppose MSP430 is the master, both RF transceiver and SD card are slaves. If it is possible, how to use the STE signal to perform slave selecting. ALL the information I've got is that the chip selecting can be done by using the STE, but no detailed examples to demonstrate it.

Thanks
 
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You can do daisy chained SPI, although I don't think that is possible in this case.
I think you can use the STE pin to select between the SD and the CC2500. You have to use a not gate and make sure only one slave is selected at a time.
connect STE directly to chip select/slave select of cc2500. Use a not gate to connect STE to chip select pin of SD.
This is not recommended though coz whenever cc2500 is not selected, SD is selected. If you are not aware and send some clk pulses you might end up receiving data from SD.
Try to use another line to slave select of SD.
 

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