ZHCSMK4A september 2022 – july 2023 ADS131B26-Q1
PRODUCTION DATA
In contrast to ADC1y and ADC3y, conversions on ADC2y are controlled by means of a channel sequencer. Figure 9-22 depicts a flow chart of the sequencer operation. The ADC2y sequencer has up to 16 sequence steps that are individually enabled or disabled using the SEQ2y_STEPn_EN bits (n = 0 to 15). Each sequence step corresponds to one single conversion of ADC2y, which means up to 16 different measurements can be taken in one sequence run. The SEQ2y_STEPn_CFG registers configure the PGA gain, and the positive and negative input for the PGA for every sequence step. When a sequence is started, the sequencer steps through all enabled sequence steps, always starting with step 0. The sequencer ignores sequence steps that are disabled. One conversion is taken by ADC2y in each step before the sequencer configures ADC2y for the next step in the sequence. After the sequencer configures ADC2y for the next sequence step, the sequencer adds a programmable delay before starting the conversion to allow for settling of the input signal. The MUX2y_DELAY[2:0] bits select the delay time globally for all sequence steps. The time required to complete a sequence is given by Equation 22:
where:
While a sequence is ongoing, the SEQ2y_ACTIVE bit is set in the STATUS register.
Do not make any changes to registers in the address range from 0x8C to 0x9F while ADC2A is enabled, and make no changes to registers in the address range from 0xCC to 0xCF while ADC2B is enabled.
To avoid false sequencer starts, follow this procedure to configure and start the sequencer:
Setting the SEQ2y_START bit while ADC2y is disabled does not start a sequence.
Conversion data for the sequence steps of ADC2y are 16 bits and (in contrast to ADC1y and ADC3y conversion data) are stored in the user register space (register addresses 10h to 2Fh). The conversion data for sequence step n are stored in the corresponding SEQ2y_STEPn_DATA register. Conversion data for a sequence step that is disabled are set to 0000h. Read ADC2y conversion data using the register read command.
The conversion data of all SEQ2y_STEPn_DATA registers only update when a sequence run of ADC2y completes. While a sequence run is ongoing, the conversion data of the previous sequence run are read from the SEQ2y_STEPn_DATA registers. There is no data corruption or mix of data from two different sequence runs, even when a sequence completes while the SEQ2y_STEPn_DATA registers are read.
The ADC2y sequencer offers three sequence modes:
The SEQ2y_MODE[1:0] bits select the sequence mode for ADC2y.