Component: UART (RS232) (Comms: Interface)

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Author Matrix Ltd
Version 3.0
Category Comms: Interface


UART (RS232) component

Low level routines for controlling or interacting with a standard asyncronous serial interface. On a microcontroller the interface will be the onboard UART which will need voltage level shifting using a max2323 to become RS232 compatible. See the EB015 RS232 E-block for details.

Component Source Code

Please click here to download the component source project: FC_Comp_Source_RS232.fcfx

Please click here to view the component source code (Beta): FC_Comp_Source_RS232.fcfx

Detailed description

Overview

The RS232 component is in fact nothing more than a TTL level asynchronous serial communications bus which basically means that there is no clock signal. Instead the data is sent out at a precise data rate specified by the Baud which is represented in bits per second. Both devices need to be set to the same rate to allow communications to work correctly.


There are two signals which make up the asynchronous serial connection: RX and TX. The receive RX signal is used for incoming data and the transmit TX signal is used for outgoing data. When connecting two devices together it is important to connect the TX of one device to the RX of the other and visa versa. When inactive the bus defaults to having the TX signal held in the high state. Each data byte sent then starts with a low signal for 1 period of the baud rate to signify that data is to follow.


Each RS232 transaction consists of a start bit (low) for a single clock cycle followed by data made up of 7/8/9 clock cycles followed by a stop bit (high) for a single clock cycle.

RS232 Bytes.jpg

TTL

By default the RS232 component will provide TTL asynchronous serial data which is best suited for a single device to single device data connection on the same circuit board. An example might be a GSM modem or GPS module. The TTL signals are normally at VCC when the bus is idle and toggles between VCC and Ground when sending data.


RS232

By adding a driver chip such as a MAX2323 the TTL signals can be upgraded to RS232 which is best suited for single device to single device mid range off board communications. The RS232 signals replace the voltages VCC with +12V and GND with -12V to allow for better noise rejection in noisy environments.


RS485

By adding a driver chip such as a MAX3078 the TTL signals can be upgraded to RS485 which is best suited for master to multiple slave type mid range off board communications.


Auto Baud

Some devices feature an auto baud functionality and is commonly triggered by sending a known data byte to the device before any other data is sent allowing the correct baud to be worked out.

Examples

Transmit

This example transmits a string "Hello World". FC6 Icon.png RS232_Example1 The Console window shows the data as it is sent and received.

RS2321.jpg


Receive

This example receives a character and outputs it to the LCD, an injector has been added to allow you to type data into the console. FC6 Icon.png RS232_Example2 The Console window has tabs for the human interface data injector allowing you to type in data that will be received by the component.

RS2322.jpg

Again the RS232 console tabs reflect the data as it is sent and received.

RS2323.jpg

LCD showing received data.

RS2324.jpg


Transmit and Receive

This example echoes back any data that is received allowing a nice sanity check when connecting an embedded device to a PC or other source of communications. FC6 Icon.png RS232_Example3 Again the RS232 console tabs reflect the data as it is sent and received.

RS2325.jpg


UART Bridge

This example allows a microcontroller with two UART peripherals to receive data one one UART and transmit on the other and visa versa in a reliable manner using interrupts. Note that this method will only work with hardware UART channels. A software UART could be done in a similar way using a falling edge type interrupt on the UART RX pin to trigger the receive function. FC6 Icon.png RS232_Example4

COM Port

The COM port property allows you to attach the RS232 component to a COM port on your PC during simulation allowing real world hardware such as RS232, Bluetooth, GPS to work with the simulation.


Injector

The Injector property allows you to select an injector component on the panel for use in the simulation. The human interface injector can be used to inject typed in data via the console window and can be seen in examples 2 and 3 above.

There are other pre-made injectors to allow you to do various aspects from simulating a generic AT terminal to simulating a specific remote device.






Macro reference

ChangeHWBaud

Fc9-comp-macro.png ChangeHWBaud
Changes the hardware UART baud rate allowing for dynamic speed changes.  
Fc9-u8-icon.png - BYTE NewBaud
0=1200, 1=2400, 2=4800, 3=9600, 4=19200, 5=38400, 6=57600, 7=115200, 8=250000 
Fc9-void-icon.png - VOID Return


Initialise

Fc9-comp-macro.png Initialise
Sets up the RS232 peripheral, must be called at the start of your program or at least before you start calling any other RS232 macros. 
Fc9-void-icon.png - VOID Return


ReceiveBinary16Bit

Fc9-comp-macro.png ReceiveBinary16Bit
Receives a binary 16-bit value split across two bytes. 
Fc9-bool-icon.png - BOOL MSBfirst
0=Least significant byte first, 1=Most significant byte first 
Fc9-u8-icon.png - BYTE Timeout
Max amount of time in ms to wait between bytes 
Fc9-u16-icon.png - UINT Return


ReceiveBinary32Bit

Fc9-comp-macro.png ReceiveBinary32Bit
Receives a binary 32-bit value split across four bytes. 
Fc9-bool-icon.png - BOOL MSBfirst
0=Least significant byte first, 1=Most significant byte first 
Fc9-u8-icon.png - BYTE Timeout
Max amount of time in ms to wait between bytes 
Fc9-u32-icon.png - ULONG Return


ReceiveBinaryFloat

Fc9-comp-macro.png ReceiveBinaryFloat
Receives a binary 32-bit floating point value split across four bytes. 
Fc9-bool-icon.png - BOOL MSBfirst
0=Least significant byte first, 1=Most significant byte first 
Fc9-u8-icon.png - BYTE Timeout
Max amount of time in ms to wait between bytes 
Fc9-f32-icon.png - FLOAT Return


ReceiveByteArray

Fc9-comp-macro.png ReceiveByteArray
Receives an array of bytes and returns the number of bytes received. 
Fc9-u8-icon.png - BYTE Data
Array to store the incoming data 
Fc9-u8-icon.png - BYTE NumBytes
Maximum number of bytes to try and receive 
Fc9-u8-icon.png - BYTE Timeout
Max amount of time in ms to wait between bytes 
Fc9-u8-icon.png - BYTE Return


ReceiveChar

Fc9-comp-macro.png ReceiveChar
Attempts to receive a single packet from the UART interface. 
Fc9-u8-icon.png - BYTE Timeout
Time to wait in milliseconds for valid data before returning, 0=Dont wait, 255=Wait forever. 
Fc9-s16-icon.png - INT Return


ReceiveFloat

Fc9-comp-macro.png ReceiveFloat
Attempts to receive a floating point number as ASCII characters and convert back into a numeric value. Note this function will receive until a timeout or a none numeric char is received, the none numeric char will be lost. 
Fc9-u8-icon.png - BYTE Timeout
Max time in ms to wait in between bytes 
Fc9-bool-icon.png - BOOL IgnoreData
0=Dont ignore any data, 1=Ignore any initial none numeric data 
Fc9-f32-icon.png - FLOAT Return


ReceiveHexNumber

Fc9-comp-macro.png ReceiveHexNumber
Attempts to receive a hex number as ASCII characters and convert back into a numeric value. Note this function will receive until a timeout or a none hexadecimal char is received, the none numeric char will be lost. 
Fc9-u8-icon.png - BYTE Timeout
Max time in ms to wait in between bytes 
Fc9-bool-icon.png - BOOL IgnoreData
0=Dont ignore any data, 1=Ignore any initial none numeric data 
Fc9-bool-icon.png - BOOL Prefix
Look for prefix before receiving, 1=0xFF, 0=FF 
Fc9-u32-icon.png - ULONG Return


ReceiveINTArray

Fc9-comp-macro.png ReceiveINTArray
Receives an array of 16-bit INT/UINT values and returns the number of values received. 
Fc9-u16-icon.png - UINT Data
Array to store the incoming data 
Fc9-u8-icon.png - BYTE NumValues
Maximum number of values to try and receive 
Fc9-bool-icon.png - BOOL MSBfirst
0=Least significant byte first, 1=Most significant byte first 
Fc9-u8-icon.png - BYTE Timeout
Max amount of time in ms to wait between bytes 
Fc9-u8-icon.png - BYTE Return


ReceiveNumber

Fc9-comp-macro.png ReceiveNumber
Attempts to receive a number as ASCII characters and convert back into a numeric value. Note this function will receive until a timeout or a none numeric char is received, the none numeric char will be lost. 
Fc9-u8-icon.png - BYTE Timeout
Max time in ms to wait in between bytes 
Fc9-bool-icon.png - BOOL IgnoreData
0=Dont ignore any data, 1=Ignore any initial none numeric data 
Fc9-s32-icon.png - LONG Return


ReceiveString

Fc9-comp-macro.png ReceiveString
Attempts to receive a string of bytes from the UART interface. 
Fc9-u8-icon.png - BYTE Timeout
Time to wait in milliseconds for valid data before returning, 0=Dont wait, 255=Wait forever. 
Fc9-u16-icon.png - UINT NumBytes
The number of bytes to try and receive, ideally your string variable should have at least 1 more byte to store the null termination byte 
Fc9-string-icon.png - STRING Return


SendBinary16Bit

Fc9-comp-macro.png SendBinary16Bit
Sends out a 16-bit binary value split across two bytes. 
Fc9-u16-icon.png - UINT Value
 
Fc9-bool-icon.png - BOOL MSBfirst
0=Least significant byte first, 1=Most significant byte first 
Fc9-void-icon.png - VOID Return


SendBinary32Bit

Fc9-comp-macro.png SendBinary32Bit
Sends out a 32-bit binary value split across four bytes. 
Fc9-u32-icon.png - ULONG Value
 
Fc9-bool-icon.png - BOOL MSBfirst
0=Least significant byte first, 1=Most significant byte first 
Fc9-void-icon.png - VOID Return


SendBinaryFloat

Fc9-comp-macro.png SendBinaryFloat
Sends out a 32-bit binary floating point value split across four bytes. 
Fc9-f32-icon.png - FLOAT Value
 
Fc9-bool-icon.png - BOOL MSBfirst
0=Least significant byte first, 1=Most significant byte first 
Fc9-void-icon.png - VOID Return


SendByteArray

Fc9-comp-macro.png SendByteArray
Transmits an array of bytes via the UART peripheral 
Fc9-u8-icon.png - BYTE Data
Data to transmit 
Fc9-u8-icon.png - BYTE NumBytes
Number of bytes to send from the array 
Fc9-void-icon.png - VOID Return


SendChar

Fc9-comp-macro.png SendChar
Sends out a single packet from the UART interface. 
Fc9-s16-icon.png - INT Char
 
Fc9-void-icon.png - VOID Return


SendFloat

Fc9-comp-macro.png SendFloat
Sends out a floating point number as an ASCII String from the UART interface. 
Fc9-f32-icon.png - FLOAT Number
 
Fc9-void-icon.png - VOID Return


SendHexNumber

Fc9-comp-macro.png SendHexNumber
Sends out a number as an ASCII hexadecimal String from the UART interface. 
Fc9-u32-icon.png - ULONG Number
 
Fc9-u8-icon.png - BYTE NumChars
Number of characters in the string data, 0 for auto, 2 for 0x00, 4 for 0x0000 
Fc9-bool-icon.png - BOOL Prefix
Generate hexadecimal prefix 0x e.g. 1= 0xFF, 0= FF 
Fc9-void-icon.png - VOID Return


SendINTArray

Fc9-comp-macro.png SendINTArray
Transmits an array of 16-bit INT/UINT values via the UART peripheral 
Fc9-u16-icon.png - UINT Data
Data to transmit 
Fc9-u8-icon.png - BYTE NumValues
Number of 16-bit values to send from the array 
Fc9-bool-icon.png - BOOL MSBfirst
0=Least significant byte first, 1=Most significant byte first 
Fc9-void-icon.png - VOID Return


SendNumber

Fc9-comp-macro.png SendNumber
Sends out a number as an ASCII String from the UART interface. 
Fc9-s32-icon.png - LONG Number
 
Fc9-void-icon.png - VOID Return


SendString

Fc9-comp-macro.png SendString
Sends out a string of bytes from the UART interface. 
Fc9-string-icon.png - STRING Data
 
Fc9-void-icon.png - VOID Return


Property reference

Fc9-prop-icon.png Properties
Fc9-conn-icon.png Comms Settings
Fc9-type-16-icon.png Channel
UART Channel selector Software channels are bit banged using generic I/O pins but are not as reliable as hardware channels. Hardware channels use the selected peripheral on-board the target microcontroller. 
Fc9-type-16-icon.png Baud Options
Baud rate option selector 
Fc9-type-14-icon.png Baud Rate
 
Fc9-type-16-icon.png Data Bits
Number of data bits 
Fc9-type-16-icon.png Return
Return data width from Receive macro. 8-bit data mode always returns a byte ranging from 0-255, 255 could mean a timeout or could be a valid data. 16-bit data mode rereturns 0-255 for valid data, 256 for a timeout, return data must be stored into an INT or UINT variable. 
Fc9-type-16-icon.png Echo
Automatically echoes back any received data when enabled by re-transmitting the received byte. 
Fc9-conn-icon.png Connections
Fc9-type-7-icon.png Use TX
Selects if the Transmit pin is used by the component. Yes: The TX pin is active and used to transmit data for the UART. No: The TX pin is disabled and free to be used as general I/O. 
Fc9-type-5-icon.png TX
Pin to be used for Transmit data 
Fc9-type-7-icon.png TX Alt Pin
Allows the TX pin to be allocated to an alternate I/O pin. 
Fc9-type-7-icon.png Use RX
Selects if the Receive pin is used by the component. Yes: The RX pin is active and used to receive data for the UART. No: The RX pin is disabled and free to be used as general I/O. 
Fc9-type-5-icon.png RX
Pin to be used for Receive data 
Fc9-type-7-icon.png RX Alt Pin
Allows the RX pin to be allocated to an alternate I/O pin. 
Fc9-type-16-icon.png Use Flow Control
Flow Control (Handshake) enable or disable. On: Two I/O pins are used to control the flow of data in and out of the device. Off: Flow control is disabled. 
Fc9-conn-icon.png Simulation
Fc9-type-10-icon.png Label
Textual label shown on the component I/O flasher 
Fc9-type-7-icon.png Scope Traces
Selects if the scope traces are automatically added to the data recorder window or not. Simulation - draws an approximation of the UART data onto the scope trace. ICT - sets up the scope trace for incoming data and adds UART packet decoding at the correct BAUD. 
Fc9-type-7-icon.png Console Data
Selects if the console data is automatically generated or not 
Fc9-type-16-icon.png Console Format
Controls if the data is shown as a log with time and date stamps or just as raw data 
Fc9-type-21-icon.png Console Columns
Number of characters that can be displayed on a single line of the console. 
Fc9-type-16-icon.png Data Source
Simulation data source used to allow the component to connect to various remote devices Nothing - Simulation data is ignored COM port - Routes the communication data to and from a physical or virtual COM port API - Routes the communication data via a data API component on the Panel.