user18748: I'm testing the SN76489AN chip with Arduino and I'm able to play the 3 tones I want etc BUT I don't understand why the READY pin is not working? The datasheet says the pin goes high when the chip is ready and low when it's busy with processing a command. But the READY pin is always low! I've got 2 brand new pieces of the chip and they both act this way. I've even tried to pull-up this pin but it didn't help. I see everyone is just using delayMicroseconds in their examples, so I guess it is a common problem but it's just strange... Is it a bug in the chip or what? Does anyone know?
Thanks!

user13432: The READY signal is open-collector. It will therefore require a pullup-resistor. Test circuit in datasheet shows a 2 kohm resistor. You could try with that. Alternatively use the internal pullup resistor on the input pin but this may be too large (weak).  
Cheers!

18748: <p>I'm testing the <strong>SN76489AN</strong> chip with Arduino and I'm able to play the 3 tones I want etc BUT I don't understand why the READY pin is not working? The datasheet says the pin goes high when the chip is ready and low when it's busy with processing a command. But the <strong>READY pin is always low!</strong> I've got 2 brand new pieces of the chip and they both act this way. I've even tried to pull-up this pin but it didn't help. I see everyone is just using <code>delayMicroseconds</code> in their examples, so I guess it is a common problem but it's just strange... Is it a bug in the chip or what? Does anyone know?</p>

<p>Thanks!</p>
 13432: <p>The READY signal is <a href="https://en.wikipedia.org/wiki/Open_collector" rel="nofollow">open-collector</a>. It will therefore require a pullup-resistor. Test circuit in datasheet shows a 2 kohm resistor. You could try with that. Alternatively use the internal pullup resistor on the input pin but this may be too large (weak).  </p>

<p>Cheers!</p>
