Nuts and Volts - September 2013

Lemos International, Inc.

Telegesis Home Automation Digilent Development Kit www.lemosint.com Cerebot MX3cK www.digilentinc.com

void formNetwork(void)
{
 txBuf[0] = 0x0D; //preamble
 txBuf[1] = 0x0A; //preamble
 txBuf[2] = ‘A’; //command
 txBuf[3] = ‘T’;
 txBuf[4] = ‘+’;
 txBuf[5] = ‘E’;
 txBuf[6] = ‘N’;
 txBuf[7] = ‘:’;
 txBuf[8] = ‘1’; //channel
 txBuf[9] = ‘1’;
 txBuf[10] = ‘,’;
 txBuf[11] = ‘3’; //power
 txBuf[12] = ‘,’;
 txBuf[13] = ‘2’; //PANID
 txBuf[14] = ‘4’;
 txBuf[15] = ‘6’;
 txBuf[16] = ‘8’;
 txBuf[17] = 0x0D; //postamble
 txBuf[18] = 0x0A; //postamble
void leaveNetwork(void)
{
 txBuf[0] = 0x0D; //preamble
 txBuf[1] = 0x0A; //preamble
 txBuf[2] = ‘A’; //command
 txBuf[3] = ‘T’;
 txBuf[4] = ‘+’;
 txBuf[5] = ‘D’;
 txBuf[6] = ‘A’;
 txBuf[7] = ‘S’;
 txBuf[8] = ‘S’;
 txBuf[9] = ‘L’;
 txBuf[10] = 0x0D; //postamble
 txBuf[11] = 0x0A; //postamble
 xmitPkt(19); //send it

Screenshot 3 says it all. The Combined Interface device is blank as far as PAN establishment is concerned. The Combined Interface device does not belong to any particular PAN and it has not established a PAN to its knowledge. The Combined Interface artillery is primed to In structure, the AT=EN: command is no different than the previous AT commands we’ve issued. Along with the base establish network AT command, we can specify a desired channel, power level, and PANID. It may take up to 16 seconds to build the network. So, we’ll mark time until network establishment response characters begin to flow into the UART2 receive buffer.

The ETRX357 is configured to echo the incoming command. We can see that in the top-most line of the network establishment response message captured in Screenshot 4. We have requested that the Combined Interface device build a PAN with a PANID of 2468 on channel 11 with a power factor of three. A success response follows, confirming the requested channel and PANID. The 64-bit EPANID is also revealed.

With the PAN established, the Combined Interface device is instructed to allow nodes to join the newly formed PAN:

void permitJoining(BYTE duration)
{
 txBuf[0] = 0x0D; //preamble
 txBuf[1] = 0x0A; //preamble
 txBuf[2] = ‘A’; //command
 txBuf[3] = ‘T’;
 txBuf[4] = ‘+’;
 txBuf[5] = ‘P’;
 txBuf[6] = ‘J’;
 txBuf[7] = ‘O’;
 txBuf[8] = ‘I’;
 txBuf[9] = ‘N’;
 txBuf[10] = ‘:’;
 txBuf[11] = duration;  //join window
 txBuf[11] = 0x0D; //postamble
 txBuf[13] = 0x0A; //postamble