RM0029 Datasheet, PDF (1028/1740 Pages) STMicroelectronics – The primary objective of this document

Enhanced Queued Analog-to-Digital Converter (EQADC)
RM0029
– Supports controls to bypass the trigger digital filters
● Two Triggers operation mode for queue0
– Additional internal trigger (not filtered) called Advance trigger that is used to
enable the external trigger of queue0 and to control the loop behavior of CFIFO0
● Supports 4 to 8 external 8-to-1 muxes which can expand the input channel number
from 40 to 96
● Upgrades the functionality provided by the QADC
25.3
25.3.1
25.3.2
Modes of operation
This section describes the operation modes of the EQADC.
Normal mode
This is the default operational mode when the EQADC is not in streaming mode or
background debug or stop mode.
Streaming mode
This mode is characterized by two main aspects: the abort action by CFIFO0 in any current
conversion process started from another queue, and the loop behavior of the CFIFO0.
In some applications, there may be sequences of identical commands each spaced only by
a few microseconds. To reduce the DMA data transfer, in this mode a short command queue
can be stored in CFIFO0 and repeatedly be executed based on a timed trigger, but advance
to the next (repeating) sequence of commands based on another device’s internal trigger.
The CFIFO0 delivers commands to the ADC as before, but those commands are not
‘invalidated’ after they are sent (in fact, they are ‘invalidated’ only because the Transfer Next
Data Pointer has moved on). When it encounters these repeated commands the CFIFO0
only fills once, using the DMA as usual, until either it is full or a command with End-of-
Queue is encountered. Thereafter the sub-queue repeats/wraps. The number of commands
loaded is unaffected by the delivery of commands once the streaming mode is configured,
since no commands loaded are invalidated even if sent before all the queue is loaded.
The number of entries in the CFIFO0 is extended to eight (configurable). This is to facilitate
the targeted applications. The repeating subqueue must be contained within the eight
CFIFO0 entries.
To maintain compatibility, CFIFO0 by default operates as it does before, without streaming
and with four entries. Streaming, and additional entries, can be enabled independently.
Streaming mode is selected as another mode for queue 0 using the configuration bits in the
EQADC_CFCR register. Streaming mode makes use of an additional bit in the Conversion
Command Word (CCW); this bit is called ‘Repeat’. The purpose of this bit is to mark in the
command queue, where to start a repeating sequence.
Streaming mode requires two trigger inputs. The standard queue 0 trigger, in this mode
referred to as ‘Repeat Trigger’ and a second internal trigger input to the eQADC called
‘Advance’ trigger.
1028/1740
Doc ID 15177 Rev 8