SBASAA5 july 2023 ADS131B23-Q1
PRODUCTION DATA
The ADS131B23-Q1 offers a missing host detection (MHD) monitor that detects when the host is not communicating with the device anymore. A watchdog timer checks the time between two SPI frames with valid commands including valid CRCs. If a valid command with a valid CRC is not received within the watchdog time window, the host is considered missing. There is no monitor fault flag that indicates a missing host, only the MHD pin is used to detect this fault.
To use the missing host detection mode, configure the GPIO0/MHD pin as output (GPIO0_DIR = 1b) and the GPIO0 source for missing host detection mode (GPIO0_SRC = 0b). When the watchdog times out, the MHD pin is set active. Enable the missing host detection mode by setting the MHD_CFG[1:0] bits to one of the three available watchdog timeout windows. To reset the MHD output after a missing host was detected, disable the missing host detection mode by setting MHD_CFG = 00b.
The actual output signal of the MHD pin when active or inactive depends on the GPIO0 format (GPIO0_FMT bit) and MHD pin polarity (MHD_POL bit) configuration. See the respective bit descriptions and the General-Purpose Digital Inputs and Outputs (GPIO0 to GPIO4) section for details. Table 8-22 shows an example where the MHD pin is configured for a static low signal in an active state, and a static high signal in an inactive state. The pin can for example also be configured for a static low signal in an active state, and a PWM output signal with 50% duty cycle in an inactive state to act as some sort of heart beat signal as long as the device detects a valid host.
REGISTER BIT | BIT SETTING | DESCRIPTION |
---|---|---|
GPIO0_DIR | 1b | GPIO0/MHD pin configured as digital output |
GPIO0_SRC | 0b | MHD selected as data source for GPIO0/MHD pin |
GPIO0_FMT | 0b | GPIO0/MHD pin configured for static output levels |
MHD_POL | 0b | MHD output is active low |