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[FAQ] TLA2518: Channel 0 does not work properly as a GPIO

Part Number: TLA2518
Other Parts Discussed in Thread: ADS7038, ADS7028

When configuring Channel 0 as a GPIO, the pin does not function as expected. 

When configured as a GPIO push pull, the pin is always high; and when GPIO0 is configured as an open drain, it is floating and will only follow the pull up provided.  

Can GPIO0 be used?


  • Hello,

    Channel 0 on the TLA2518 can be used as a GPIO.

    Unfortunately there is a limitation on the device due to a digital window comparator, that is not supported, controlling an ALERT function that is also not supported on this device. This ALERT is mapped to channel 0 by default, which is a limiting factor in the TLA2518.

    This means that when channel 0 is used at a digital output, the logic state is being controlled by the output of a nonsupport digital comparator. 

    To control CH0 digital output, you will need to use the ALERT_LOGIC field, of ALERT_PIN_CFG Register (Address = 0x17). See register breakdown below.

    1. ALERT_LOGIC = active high; means digital output CH0 will stay low 

    2. ALERT_LOGIC = active low; means digital output CH0 will stay high 

    In devices where the ALERT function and digital comparator is supported, ADS7038 & ADS7028, the default channel that the ALERT output is mapped to is channel 0, thus these device will also encounter a similar issue if GPO0 is to be controlled by the user. The above method will also work if all eight channels are to be used as GPIOs. 

    If not all channels are to be used as GPIO, but channel 0 is a GPO, then the ALERT output can be mapped to another channel using the ALERT_PIN[3:0]. 

    We are working on adding this to the datasheets.