Diff: doc/key_topics.md

Branch:

v2.0

Revision:

27:567abf893938

Parent:

26:12d0204be712

diff -r 12d0204be712 -r 567abf893938 doc/key_topics.md
--- a/doc/key_topics.md	Mon Mar 26 14:50:05 2018 +0000
+++ b/doc/key_topics.md	Mon Mar 26 20:28:05 2018 +0100
@@ -174,33 +174,57 @@
 in later sections below.
 
 ## Sequence Order {#measurementcycles_sequence}
-The sequence is constructed according to which channels are enabled and how many
-measurements must be performed per channel.  The arrangement is similar to
-round-robin scheduling - a measurement is carried out on each enabled channel,
-in ascending channel order, and then the loop is repeated until the requested
-number of measurements on each channel has been satisfied.
+The sequence is constructed according to a number of configurable parameters:
+- which channels are enabled
+- number of measurements to be performed per channel
+- channel priorities
+- cycle type selection
+
+When the selected cycle type is @ref ADI_SENSE_1000_CYCLE_TYPE_FULL,
+the full number of requested measurements is carried out on a channel before
+advancing to the next channel in the sequence.  Channels are visited in
+priority/ascending order.
+
+When the selected cycle type is @ref ADI_SENSE_1000_CYCLE_TYPE_SWITCH,
+the arrangement is similar to round-robin scheduling - a measurement is carried
+out on each enabled channel, in priority/ascending channel order, and then the
+loop is repeated until the requested number of measurements on each channel has
+been satisfied.
 
-For example, lets say channels [0, 3, 4, 5] are enabled, with
-measurementsPerCycle set as follows:
+By default, channels are arranged in the measurement sequence based on ascending
+order of channel ID.  However, a priority-level may be specified per channel to
+force a different ordering of the channels, with higher-priority channels
+appearing before lower-priority channels. Channels with equal priority are
+ordered by ascending order of channel ID.  Lower numbers indicate higher
+priority, with 0 being the highest.
 
-channelId | measurementsPerCycle
---------- | --------------------
-    CJC_1 | 4
- SENSOR_0 | 2
-    I2C_1 | 3
-    SPI_0 | 1
+For example, lets say channels [0, 3, 4, 5] are enabled, with cycleType as @ref
+ADI_SENSE_1000_CYCLE_TYPE_SWITCH, and measurementsPerCycle and priority
+(0=highest) set as follows:
+
+channelId | priority | measurementsPerCycle
+--------- | -------- | --------------------
+    CJC_1 | 1        | 4
+ SENSOR_0 | 2        | 2
+    I2C_1 | 0        | 3
+    SPI_0 | 2        | 1
 
 The length of the sequence would be 10 measurements in total, and the order in
 which the channel measurements appear in the sequence would look like this:
 
-| **CJC_1** | **SENSOR_0** | **I2C_1** | **SPI_0** | **CJC_1** | **SENSOR_0** | **I2C_1** | **CJC_1** | **I2C_1** | **CJC_1** |
+| **I2C_1** | **CJC_1** | **SENSOR_0** | **SPI_0** | **I2C_1** | **CJC_1** | **SENSOR_0** | **I2C_1** | **CJC_1** | **CJC_1** |
 
 When measurement data samples are retrieved from the ADISENSE by the host
 application, this is the order in which those data samples will appear.
 
-The ADSNS1000 module has 11 measurement ports however when ADXL used on the SPI
-port this equates to 3 measurements. The ADSNS1000 allows for a maximum of 128
-measurementsPerCycle. Therefore a single cycle can produce a maximum of 1664
+Changing the cycleType to @ref ADI_SENSE_1000_CYCLE_TYPE_FULL in the example above
+would generate the following sequence:
+
+| **I2C_1** | **I2C_1** | **I2C_1** | **CJC_1** | **CJC_1** | **CJC_1** | **CJC_1** | **SENSOR_0** | **SENSOR_0** | **SPI_0** |
+
+The ADSNS1000 module has 11 measurement ports; however, when ADXL used on the
+SPI port this equates to 3 measurements. The ADSNS1000 allows for a maximum of
+128 measurementsPerCycle. Therefore a single cycle can produce a maximum of 1664
 measurements. In other words, the maximum length of the sequence is 1664.
 
 ## Sequence Timing {#measurementcycles_timing}
@@ -448,4 +472,3 @@
 the top-level header and appends each table and also fills some fields within
 the table descriptors (e.g. length, CRC).  Please refer to the "user_lut_data"
 application example for an illustration of how this function can be used.
-