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

In summary, the conversation discusses the use of SPI mode to interface a eZ430-RF2500 with a Sandisk Secure Digital Card. The issue at hand is whether the MSP430 microcontroller, acting as the master, can use the same set of input wires to connect with both the RF transceiver and the SD card. The solution proposed is to use the STE signal to select between the two slaves, but caution is advised due to the possibility of receiving data from the SD card unintentionally. It is suggested to use a separate line for slave selecting of the SD card.
  • #1
mz8e08
3
0
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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  • #2
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.
 
  • #3
for your question! Using SPI mode to interface the MSP430 with both the RF transceiver and SD card is definitely possible. In this setup, the MSP430 would act as the master and the RF transceiver and SD card would be slaves. The SOMI, SIMO, SCK, and STE pins can be shared between the two devices, but you will need to use the STE pin to select which device you want to communicate with. The STE pin is used to enable and disable the slave devices, so you will need to toggle this pin to select which device you want to communicate with. As for specific examples, you may need to refer to the datasheets or user manuals for the specific devices you are using for more detailed guidance on how to use the STE pin for slave selection. Overall, using SPI mode to interface the MSP430 with both the RF transceiver and SD card can be a powerful and efficient way to communicate between these devices. Good luck with your project!
 

1. What is SPI mode and how does it work?

SPI (Serial Peripheral Interface) is a synchronous serial communication protocol used for communication between microcontrollers, sensors, and other devices. It uses a master-slave architecture, where the master device controls the communication and timing. The data is transmitted through a series of bits, with a clock signal to synchronize the transfer.

2. Why is SPI mode used to interface the msp430 with RF transceiver and SD card?

SPI mode is commonly used for interfacing with low-speed peripherals such as RF transceivers and SD cards. It is a simple and efficient way to transfer data between devices, and it allows for multiple devices to be connected to the same bus.

3. How do I set up SPI mode on my msp430 microcontroller?

To use SPI mode on an msp430 microcontroller, you will need to configure the SPI pins and registers. This typically involves selecting the appropriate clock speed, data format, and communication mode. You will also need to enable the SPI module and configure the chip select pins for each device you are interfacing with.

4. Can I use SPI mode to transfer data bidirectionally?

Yes, SPI mode can support bidirectional data transfer. This is typically achieved by using separate data lines for sending and receiving data, or by using a half-duplex communication mode where data is sent and received on the same line but at different times.

5. Are there any limitations to using SPI mode for communication between the msp430, RF transceiver, and SD card?

While SPI mode is a widely used and versatile communication protocol, it does have some limitations. The maximum data transfer rate is limited by the clock speed and the length of the data lines. Additionally, it may not be suitable for long-distance communication or high-speed data transfer. It is important to carefully consider the requirements of your specific application before choosing to use SPI mode for interfacing these devices.

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