UART basics

The 1232 has an USCI module. How it works is described in the 2x family users guide, "universal serial communications contreoller - UART mode" chapter.
Demo code should be available from the MSPs product page.

There are also many threads about serial connections in this forum.

abhishek Sabnis said:

Also I want  to do communication between ST micro micro-controller and TI MSP430. Please tell me the starting point.

Starting point is to chose a communication protocol.
You can communicate in a wide adn almost unlimited number of ways. Direct or through RF, using UART, SPI, I2C or GPIO.
Which one to chose depends on your project parameters.

Your question is like standing in the middle of a large market place, shouting 'I want to eat! What shall I buy?"

Thanks jens for your reply.

As far as communication between ST micro and TI msp430 i want to do it through UART. hence, if some one have app notes on communication of msp430 to other micro through UART let me know.

Thanks,

abby

abhishek Sabnis said:

if some one have app notes on communication of msp430 to other micro through UART let me know.

UART is UART. It is normed by CCITT. The only uncertain parameters are the voltage levels. RS232 (used by PC COM ports) uses +-3V..12V signals (negative voltages being '1', 0V is invalid) while TTL-like implementations, such as the MSP UARTs use 0V/VCC for '0' and '1'. Mso tother micros do it the same way.
One possible problem could be if the other micro uses a different VCC (e.g. 5V).

There's an appnot ont eh Ti website abotu interfacing 5V peripherals with an MSP. Usually, MSP outputs to 5V inputs don't require special attention (as long as the MSPs VCC is above the other side's high threshold - see datasheets). 5V outputs to MSP inputs can be handled in three ways.
First using a dedicated voltage level shifter. There ar elots of logic ICs wiht two supply voltages, separate for input and output side.
Second is a diode and a pullup on the MSP side of the diode. So the pullup will pull the input voltage to MSPs VCC, while the 5V peripheral can only pull it low. You'll need a schottky diode, so you won't have too much voltage drop above VSS/GND then.
Third method is a simpel series resistor that keeps the current low. All MSP port pins have internal clamp diodes which route over/undervoltages to VCC/VSS. The current must not exceed 2mA, So in case of MSP-VCC of 3V, the maximum overvoltage is 5V-3V=2V and a resistor >1k will keep the clamp current below maximum. 4.7k would be a good value.
The cheaper the method is, the more current it wastes for the signal conversion. :)

For using (programming)  an UART, there are many threads in thsi forum, and also demo codes which are linked form the MSP product page.

Thanks jens.

So to start with playing on UART with no external hardware. how can check i have correct firmware and my TX and RX is working? Can i use my computer to send and receive commands? if yes then how?

abhishek Sabnis said:

how can check i have correct firmware and my TX and RX is working?

One option is to enable the loopback function. Then everything sent will be received too. (you may as well connect RX and TX pins externally).

abhishek Sabnis said:

Can i use my computer to send and receive commands? if yes then how?

Yes, sure. You'll need additional hardware. One option is an USB->serial converter with TTL output signals (put a 4.7k series resistor on the RX and TX connection if the converter has 5V output signals).
The other option is a level shifter such as the MAX3232. Then you can connext the MAX output signals to a PCs COM port or to a normal USB->RS232 converter.

On the PC side you can use a terminal program such as the HyperTerm (included in windows up to XP), Putty or any other. Just select the COM port (in case of an USB converter, the virtual COM port provided by the converter driver) and select the same baudrate and communication parameters (data bits, stop bits) as on the MSP (and disable hardware and software handshake).