evolve

Serial Port

Evolve has support built in for serial ports this goes back to its original core as being a language for embedded software engineers who usually have a debug port out of the processor for sending and receiving debug information.

Basic Communications

Opening and closing a port

A port can be opened with the ser_open command which takes three argument the first is a boolean which it gets set to true if the port was opened successfully. The second is an integer which gets set to the port id this is used to direct an function to the port. The third is the port name e.g. COM1.

ser_open PortOpen PortId “COM1”

The port can be checked to see if it is open by the ser_isopen command which sets its argument to true true if the port is open.

The port is closed with the ser_close command.

Sending Data

Data can be sent with the ser_tx command this takes three arguments the first is used to return the actual number of bytes sent, the second argument should be a byte list containing the data to send or a string to send, other variables will be sent as their string representation. The third argument is the number of bytes to send.

Data[10] = 0x00

ser_tx BytesSent PortId Data 5

The above code would send the first 5 bytes of data from the Data list, the number of bytes sent could be confirmed by checking the value of BytesSent.

Receiving Data

Data is received with the ser_rx command this takes the same three arguments as ser_tx but the first argument gets set to the number of actual bytes received and the buffer is set to the received data. If the receive buffer is not the same size as the buffer size set in the fourth argument then the buffer will be resized to the defined size.

Data[10] = 0x00

ser_tx BytesRecieved Data PortId 5

If the above code was used upon completion the number of elements in Data would be 5 and BytesRecieved would be set to the number of bytes read by the port.

The following example creates a byte list and sends it out on Com port 3 it then receives the data back and verifies it. To run this code you need to connect the RX and TX pins on your serial port.

//---------------------------------------

// File: serialport.e

//---------------------------------------

// Block: go

//---------------------------------------

block Go

//open the port

ser_open Open Id "COM4"

// check port open

if Open == false

outl "Cant open port"

exit_program

_if

//adjust settings

ser_baudrate Id #BAUD115200

ser_bytesize Id 8

ser_stopbits Id #STOPBITONE

ser_parity Id #PARITYNONE

outl "Port Open"

//create a byte list full of data

ByteVar = 0xff

Index = 0

while Index < 100

ByteVar[Index] = Index

++ Index

_while

//send the data

ser_tx BytesSent Id ByteVar 100

//check the bytes sent

outl "Bytes Sent: " BytesSent

//create a byte to RX the data into

ByteVarRX = 0xff

//read the data

ser_rx BytesRxed ByteVarRX Id 100

//check the bytes RXed

out "Bytes Received: "

outl BytesRxed

Index = 0

while Index < 100

if ByteVarRX[Index] != Index

outl "Error: " Index

exit_program

_if

++ Index

_while

outl "Test complete ok"

//send the data

ser_tx BytesSent "const" Id 5

ser_rx BytesRxed ByteVarRX Id 5

//check the bytes RXed

out "Bytes Received: "

outl BytesRxed

Test = "TestMessage"

//send the data

ser_tx BytesSent Id Test 11

ser_rx BytesRxed ByteVarRX Id 11

//check the bytes RXed

out "Bytes Received: "

outl BytesRxed

ser_close Id

_block

Getting Port Names

To get the names of the ports on the computer the ser_getports command is used this has two arguments the first is an integer which gets set to the number of ports found, and the second a string list which gets set to the port Ids.

//---------------------------------------

// File: FindSerialPorts.e

//---------------------------------------

// Block: go

//---------------------------------------

block Go

ser_getports NumberPorts PortIds

if NumberPorts == 0

outl "No Ports"

else

I = 0

while I < NumberPorts

outl PortIds[I]

++ I

_while

_if

_block

Setting Up the port

The default setup for the port is 115200bps, 8 data bits one stop bit, even parity and no hardware control.

The settings can be changed after the port is open with the following commands.

ser_baudrate This command sets the baud rate the and can be set to the following values.

#BAUD110, #BAUD300, #BAUD600, #BAUD1200, #BAUD2400, #BAUD4800, #BAUD9600, #BAUD14400, #BAUD19200, #BAUD38400, #BAUD57600, #BAUD115200, #BAUD128000, #BAUD256000

ser_dtrcontrol This command sets the DTR control the and can be set to the following values.

#DTRCONTROLDISABLE, #DTRCONTROLENABLE, #DTRCONTROLHANDSHAKE

ser_rtscontrol This command sets the RTS control the and can be set to the following values.

#RTSCONTROLDISABLE, #RTSCONTROLENABLE, #RTSCONTROLHANDSHAKE, #RTSCONTROLTOGGLE

ser_bytesize This command sets the byte size.

ser_parity This command sets the parity and can be set to the following values.

#PARITYNONE, #PARITYODD, #PARITYEVEN, #PARITYMARK, #PARITYSPACE

ser_stopbits This command sets the number of stop bits and can be set to the following values.

#STOPBITONE, #STOPBITSONE5, #STOPBITSTWO

ser_xonchar This command sets the XON character to the passed value.

ser_xoffchar This command sets the XOFF character to the passed value.