* Simple function to sent a char at a time to Sprintf(checksum_str, "*X\n", CHECKSUM) Unsigned int CHECKSUM = gps_CRC16_checksum(datastring) // Calculates the checksum for this datastring Snprintf(datastring,80,"RTTY TEST BEACON RTTY TEST BEACON") // Puts the text in the datastring This example code is in the public domain. RTTY code from Rob Harrison Icarus Project. You can uncomment the relevant lines out as needed. To get round this we do two delays of 10000µS.ģ00 baud after some playing seemed to be stable around 3370µS delay ( 300 baud should be 1/300s = 3333µS). Theoretically 50 baud should be 1/50th of a second = 20000µS however the Arduino delayMicroseconds command can only do a maximum delay of 16383µS. The key to getting the baud rate correct is the timing. The datastring variable is passed to a procedure called rtty_txtstring which takes care of transmitting the data by breaking it down into characters, then it transmits the individual bits of those characters. Also the code adds a CRC checksum at the end of the data string. Using the circuit discussed in the previous article upload the following code will transmit a short sentence at 50 baud, 7 bits ASCII 2 stop bits. In this article we go one step further and turn this into a transmission of data. In part 1 of this article I discussed linking the NTX2B to the Arduino and getting a high and low tone out of it.
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