ADS1115 ALERT/RDY pin not responding after conversion

Hi Luis,

Sorry that is a typo. The code segment I use for setting the registers is:

	---------------------------------------------------------------------------------------

	HiByte = Cmd_ptr[3];   				// set mux channel (0 to 3)
	HiByte <<= 4;						// MUX chl << 4 to align to bits 4,5,6
	HiByte |= 0x45;					 // MUX chl | 0x45 = OS=0, MUX2=1 (single ended), PGA= 2,  and single shot 
	LoByte = 0xE3;						// DR=860s/s,comp disabled

 I2C_RegistorWrite(ADS1115_ADDRESS,0x02,0x7F,0xFF); //set LO Threshold reg
	I2C_RegistorWrite(ADS1115_ADDRESS,0x03,0x80,0x00); //set HI thresehold reg
	I2C_RegistorWrite(ADS1115_ADDRESS,0x01,HiByte,LoByte); 

 ------------------------------------------------------------------------------------------

Where the value after the ADS1115_ADDRESS is the ADC register address i.e., 0x02, 0x03, and 0x01

Does the order of writing to the registers matter??

Thanks for any input...This should not be this hard :(

Paul

Hello Paul,

I believe the COMP_QUE registers need to be set to '00' to assert after one conversion; if set to '11' the pin is disabled.    So you may try setting the Lo_byte = 0xE0

	---------------------------------------------------------------------------------------

	HiByte = Cmd_ptr[3];   	// set mux channel (0 to 3)
	HiByte <<= 4;			// MUX chl << 4 to align to bits 4,5,6
	HiByte |= 0x45;			// MUX chl | 0x45 = OS=0, MUX2=1 (single ended), PGA= 2,  and single shot 
	LoByte = 0xE0;			// DR=860s/s,  Assert after one conversion

 ------------------------------------------------------------------------------------------

Please let me know if this does not solve the issue.

Thank you and Best Regards,

Luis

Luis,

I "think" I tried that and the ALERT/RDY pin goes LOW and stays LOW.

Page 15 of the data sheet (last sentence) says "When in single-shot shutdown mode, the ALERT/RDY pin asserts low at the end of a conversion if the COMP_POL bit is set to '0'.

Do I read that to say that at the end of conversion the ALERT/RDY pin assets low and stays low till another conversion is started?

What happens if the COMP_POL bit is set to '1'?

I've been under the impression that the ALERT/RDY pin is high in single-shot mode and only asserts low for a short period (~8uS) after conversion then returns high.

I'll retry that when I get back in (Friday) and let you know the result.

Thanks for your input,

Paul

Hi Paul,

In single shot mode with COMP_POL =1 (Active High), the RDY pin asserts high after a conversion and stays high after the conversion until the user triggers the next conversion.

In single shot mode with COMP_POL=0 (Active Low), the RDY pin asserts low after a conversion and stays low after the conversion until the user triggers the next conversion.

In order to use the ALERT/RDY as a conversion ready pin, the user needs to set the COMP_QUE register to '00' to assert after a single conversion, and needs to set the MSB of the high threshold register to '1' and the MSB of the low threshold register to '0".

Please let me know if the issue persists after setting the COMP_QUE register to '00' 

Thank you and Best Regards,

Luis

Hi Luis,

I was able to get the ALERT/RDY pin to work correctly. Thank you for your last post.

Although the data sheet is very verbose it would be great if it was edited to add some configuration examples or register configurations for each operating mode. Also missing is timing diagrams for single-shot with ALERT/RDY asserts.

But thank you again for your help.

Paul