Teensy Serial Communication

[JRSmile]

Hi there,

long time not seen.

attached you find a little example on how to communicate with a teensy 3.0 via serial com port (USB emulated).

the code uses the udf from Martin Gibson which is perfect for this kind of stuff.

if you run the example the correct com port is chosen by the driver description and then a connection is opened to the teensy to send text to the device.

on the arduino side the text is converted to a {ENTER} delimited string and written to the EEPROM of the device so no other components are necessary.

when sending an empty string via the Teensy-Read() Function the device spits back the stored string via serial into the application.

this is it.

of course this is a POC and has its limitations so currently the buffer size is limited to a 50xChar string.

but i find this easy enough to publish.

ps: you need the arduino environment 1.0.4, teensydurino in the newest version from pjrc.com, and a teensy to make this work.

autoit code:

#include "CommMG.au3"


$tset = _ComGetPortNames()
for $i = 0 to UBound($tset,0) -1
if $tset[$i][1] = "USB Serial (Communication Class, Abstract Control Model)" Then
$port = StringTrimLeft($tset[$i][0],3)
EndIf
Next

Teensy_Write("Hallo Welt!",$port)
ConsoleWrite(Teensy_Read($port))


Func Teensy_Write($text,$port)
Local $result
_CommSetport($port, $result, 115200, 8, 'none', 1, 1)
_CommSendString($text & @LF)
ConsoleWrite(_CommGetString())
_Commcloseport(True)
EndFunc ;==>Teensy_Read

Func Teensy_Read($port)
Local $result
_CommSetport($port, $result, 115200, 8, 'none', 1, 1)
_CommSendString(@LF)
ConsoleWrite(_CommGetString())
_Commcloseport(True)
EndFunc ;==>Teensy_Read

arduino code:

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//
// EEPROM utility functions with usage example
//
// This example defines some utility functions
// to write byte arrays, integers and strings
// to eeprom and read them back.
//
// Some usage examples are provided.

#include <EEPROM.h>

//
// Absolute min and max eeprom addresses.
// Actual values are hardware-dependent.
//
// These values can be changed e.g. to protect
// eeprom cells outside this range.
//
const int EEPROM_MIN_ADDR = 0;
const int EEPROM_MAX_ADDR = 511;

//
// Initialize eeprom memory with
// the specified byte.
// Default value is 0xFF.
//
void eeprom_erase_all(byte b = 0xFF) {
int i;
for (i = EEPROM_MIN_ADDR; i <= EEPROM_MAX_ADDR; i++) {
EEPROM.write(i, b);
}
}

//
// Dump eeprom memory contents over serial port.
// For each byte, address and value are written.
//
void eeprom_serial_dump_column() {
// counter
int i;
// byte read from eeprom
byte b;
// buffer used by sprintf
char buf[10];
for (i = EEPROM_MIN_ADDR; i <= EEPROM_MAX_ADDR; i++) {
b = EEPROM.read(i);
sprintf(buf, "%03X: %02X", i, b);
Serial.println(buf);
}
}

//
// Dump eeprom memory contents over serial port in tabular form.
// Each printed row shows the value of bytesPerRow bytes
// (by default 16).
//
void eeprom_serial_dump_table(int bytesPerRow = 16) {
// address counter
int i;
// row bytes counter
int j;
// byte read from eeprom
byte b;
// temporary buffer for sprintf
char buf[10];

// initialize row counter
j = 0;
// go from first to last eeprom address
for (i = EEPROM_MIN_ADDR; i <= EEPROM_MAX_ADDR; i++) {
// if this is the first byte of the row,
// start row by printing the byte address
if (j == 0) {
     sprintf(buf, "%03X: ", i);
     Serial.print(buf);
}
// read current byte from eeprom
b = EEPROM.read(i);
// write byte in hex form
sprintf(buf, "%02X ", b);
// increment row counter
j++;
// if this is the last byte of the row,
// reset row counter and use println()
// to start a new line
if (j == bytesPerRow) {
     j = 0;
     Serial.println(buf);
}
// else just print the hex value with print()
else {
     Serial.print(buf);
}
}
}

//
// Returns true if the address is between the
// minimum and maximum allowed values,
// false otherwise.
//
// This function is used by the other, higher-level functions
// to prevent bugs and runtime errors due to invalid addresses.
//
boolean eeprom_is_addr_ok(int addr) {
return ((addr >= EEPROM_MIN_ADDR) && (addr <= EEPROM_MAX_ADDR));
}

//
// Writes a sequence of bytes to eeprom starting at the specified address.
// Returns true if the whole array is successfully written.
// Returns false if the start or end addresses aren't between
// the minimum and maximum allowed values.
// When returning false, nothing gets written to eeprom.
//
boolean eeprom_write_bytes(int startAddr, const byte* array, int numBytes) {
// counter
int i;
// both first byte and last byte addresses must fall within
// the allowed range
if (!eeprom_is_addr_ok(startAddr) || !eeprom_is_addr_ok(startAddr + numBytes)) {
return false;
}
for (i = 0; i < numBytes; i++) {
EEPROM.write(startAddr + i, array[i]);
}
return true;
}

//
// Reads the specified number of bytes from the specified address into the provided buffer.
// Returns true if all the bytes are successfully read.
// Returns false if the star or end addresses aren't between
// the minimum and maximum allowed values.
// When returning false, the provided array is untouched.
//
// Note: the caller must ensure that array[] has enough space
// to store at most numBytes bytes.
//
boolean eeprom_read_bytes(int startAddr, byte array[], int numBytes) {
int i;
// both first byte and last byte addresses must fall within
// the allowed range
if (!eeprom_is_addr_ok(startAddr) || !eeprom_is_addr_ok(startAddr + numBytes)) {
return false;
}
for (i = 0; i < numBytes; i++) {
array[i] = EEPROM.read(startAddr + i);
}
return true;
}

//
// Writes an int variable at the specified address.
// Returns true if the variable value is successfully written.
// Returns false if the specified address is outside the
// allowed range or too close to the maximum value
// to store all of the bytes (an int variable requires
// more than one byte).
//
boolean eeprom_write_int(int addr, int value) {
byte *ptr;
ptr = (byte*)&value;
return eeprom_write_bytes(addr, ptr, sizeof(value));
}

//
// Reads an integer value at the specified address.
// Returns true if the variable is successfully read.
// Returns false if the specified address is outside the
// allowed range or too close to the maximum vlaue
// to hold all of the bytes (an int variable requires
// more than one byte).
//
boolean eeprom_read_int(int addr, int* value) {
return eeprom_read_bytes(addr, (byte*)value, sizeof(int));
}

//
// Writes a string starting at the specified address.
// Returns true if the whole string is successfully written.
// Returns false if the address of one or more bytes
// fall outside the allowed range.
// If false is returned, nothing gets written to the eeprom.
//
boolean eeprom_write_string(int addr, const char* string) {
// actual number of bytes to be written
int numBytes;
// we'll need to write the string contents
// plus the string terminator byte (0x00)
numBytes = strlen(string) + 1;
return eeprom_write_bytes(addr, (const byte*)string, numBytes);
}

//
// Reads a string starting from the specified address.
// Returns true if at least one byte (even only the
// string terminator one) is read.
// Returns false if the start address falls outside
// or declare buffer size os zero.
// the allowed range.
// The reading might stop for several reasons:
// - no more space in the provided buffer
// - last eeprom address reached
// - string terminator byte (0x00) encountered.
// The last condition is what should normally occur.
//
boolean eeprom_read_string(int addr, char* buffer, int bufSize) {
// byte read from eeprom
byte ch;
// number of bytes read so far
int bytesRead;
// check start address
if (!eeprom_is_addr_ok(addr)) {
return false;
}
// how can we store bytes in an empty buffer ?
if (bufSize == 0) {
return false;
}
// is there is room for the string terminator only,
// no reason to go further
if (bufSize == 1) {
buffer[0] = 0;
return true;
}
// initialize byte counter
bytesRead = 0;
// read next byte from eeprom
ch = EEPROM.read(addr + bytesRead);
// store it into the user buffer
buffer[bytesRead] = ch;
// increment byte counter
bytesRead++;
// stop conditions:
// - the character just read is the string terminator one (0x00)
// - we have filled the user buffer
// - we have reached the last eeprom address
while ( (ch != 0x00) && (bytesRead < bufSize) && ((addr + bytesRead) <= EEPROM_MAX_ADDR) ) {
// if no stop condition is met, read the next byte from eeprom
ch = EEPROM.read(addr + bytesRead);
// store it into the user buffer
buffer[bytesRead] = ch;
// increment byte counter
bytesRead++;
}
// make sure the user buffer has a string terminator
// (0x00) as its last byte
if ((ch != 0x00) && (bytesRead >= 1)) {
buffer[bytesRead - 1] = 0;
}
return true;
}

//
// SETUP
//
const int BUFSIZE = 50;
char buf[BUFSIZE];
String name = "";
boolean nameEntered = false;
void setup() {
int i;
delay(5000);
Serial.begin(115200);
//strcpy(buf, "Arduino eeprom utility functions.");
//Serial.println("Saving string to eeprom...");
//eeprom_write_string(100, buf);
Serial.println("Reading string from eeprom...");
eeprom_read_string(100, buf, BUFSIZE);
Serial.print("String read: '");
Serial.print(buf);
Serial.println("'");
}

//
// LOOP
//
void loop() {
// If new data has been entered,
// read each character into the name variable.
while (Serial.available()) {
char readChar = (char)Serial.read();

// If the next character is a linefeed (enter)
// the name is complete. Exit the while() loop.
if (readChar == '\n') {
     nameEntered = true;
     continue;
}
// If the character wasn't enter, add it to the name string.
name += readChar;
}

// If a name has been entered (followed by \n)
// print "Hello name!"
if (nameEntered) {
if (name != ""){
name.toCharArray(buf,50);
//strcpy(buf, name);
eeprom_write_string(100, buf);
Serial.print("String: '");
Serial.print(name);
Serial.println("' saved to EEPROM!");
}
else
{
     eeprom_read_string(100, buf, BUFSIZE);
     Serial.print("String read: '");
     Serial.print(buf);
     Serial.println("'");
}
// Once the name has been printed, erase it and start over.
name = "";
nameEntered = false;
}
}

Edited April 29, 2013 by JRSmile