In autonomous mode, the ADC can be programmed to monitor the voltage applied on the analog input pins. The ADC generates a signal on the ALERT pin when the programmable high or low threshold values are crossed. The host processor can read the ADC conversion results from the internal data buffer.

In autonomous mode, the first start of conversion must be provided by the host and the ADC generates the subsequent start of conversions. The ADC initiates the following start of conversions using the internal oscillator.

After configuring the operation mode to autonomous mode (set the OPMODE_SEL register to 110b), as illustrated in Figure 7-11, steps for operating the ADC to be in different autonomous modes are illustrated in Figure 7-14.

A. For setting the operation mode to Autonomous modes, see Figure 7-11.

B. Select channels in the AUTO_SEQ_CHEN register.

C. Select the oscillator by configuring the OSC_SEL register and configure the NCLK_SEL register.

D. Select the data buffer mode in the DATA_BUFFER_OPMODE register.

E. Configure the thresholds in the DWC_xTH_CHx_xxx registers and hysteresis in the DWC_HYS_CHx registers. Enable the alert for channels in the ALERT_CHEN register and set the DWC_BLOCK_EN bit in the ALERT_DWC_EN register.

F. Set the bit SEQ_START bit in the START_SEQUENCE register.

G. Read the ALERT_LOW_FLAGS and ALERT_HIGH_FLAGS registers.

H. Reset the ALERT_LOW_FLAGS and ALERT_HIGH_FLAGS registers by writing 03h.

I. See the Section 7.3.7.2 section.

J. Select another operation mode in the OPMODE_SEL register.

K. For reading and writing registers, see the Section 7.5 section.

Figure 7-14 Configuring ADC in Autonomous Modes

Abort the present sequence by setting the SEQ_ABORT bit in the ABORT_SEQUENCE register before changing the ADC operation mode or ADC configuration.