Sending IR signals to Robosapien using Arduino

Question

I am trying to send commands to a Robosapien (first generation) using an IR LED hooked up to an Arduino. I have seen web pages on attaching a microcontroller directly to the toy, but what I want to do is just send commands via IR.

I found an article by K. Smith that mentioned that the IR commands sent by the Robosapien remote take the following form:

To send the hex code 85:

The IRout signal is held high until a signal is sent. Then a string of five zeros is sent to signify a command is coming. Then the hex code is sent but instead of sending a ‘1’ a ‘1110’ is sent and rather than a ‘0’ a ‘10’ is sent. So 85ドル looks like this:

Binary: 1 0 0 0 0 1 0 1
Robosapien: 1110 10 10 10 10 1110 10 1110

So I tried the code below:

int bitTime=833; 
int IROut = 4; 
// The setup() method runs once, when the sketch starts
void setup() { 
 // initialize the IR digital pin as an output:
 pinMode(IROut, OUTPUT); 
 Serial.begin(9600);
}
void test()
{
 // output high
 digitalWrite(IROut,HIGH);
 delay(1000);
 // 5 zeros
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,HIGH);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,HIGH);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,HIGH);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,HIGH);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 // send 1110 10 10 10 1110 10 1110
 // 1110
 digitalWrite(IROut,HIGH);
 delayMicroseconds(3*bitTime);
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 // 10
 digitalWrite(IROut,HIGH);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 // 10
 digitalWrite(IROut,HIGH);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 // 10
 digitalWrite(IROut,HIGH);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 // 1110
 digitalWrite(IROut,HIGH);
 delayMicroseconds(3*bitTime);
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 // 10
 digitalWrite(IROut,HIGH);
 delayMicroseconds(bitTime);
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 // 1110
 digitalWrite(IROut,HIGH);
 delayMicroseconds(3*bitTime);
 digitalWrite(IROut,LOW);
 delayMicroseconds(bitTime);
 // output high
 digitalWrite(IROut,HIGH);
 delay(1000);
}
void loop() 
{ 
 test();
}

But unfortunately I am not getting any response from the Robosapien. What am I doing wrong?

• Axeman: Uhm... are you using external components to modulate the IR signal over the 39.something KHz carrier?

Answer 1

A bit time of 833 µs implies a data rate of 1200 bps. I don't know anything about Robosapien, but my first thought is that this signal is possibly meant to be the keying (envelope) imposed on a higher-frequency (e.g., 38 kHz) IR carrier signal.

Can you provide a link to the K. Smith article for reference?

• Axeman: Precisely. Robosapien AFAIR (I've played with that thing years ago) asks for a 1200 bps signal over a 39.2 KHz carrier.
• M-V: Thanks, Dave. Here is the link to the article: docstoc.com/docs/27902404/Robosapien-Project
• M-V: Dave, you've pointed me in the right direction. This is all new stuff to me - I'll look into how to generate the carrier signal.