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| -rw-r--r-- | .gitignore | 1 | ||||
| -rw-r--r-- | doc/datafmt/Makefile | 2 | ||||
| -rw-r--r-- | doc/datafmt/datafmt.ms | 140 |
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@@ -15,6 +15,7 @@ _autosave* *.out *.pdf *.png +*.ps *.run.xml *.stl *.toc diff --git a/doc/datafmt/Makefile b/doc/datafmt/Makefile new file mode 100644 index 0000000..0cc3afe --- /dev/null +++ b/doc/datafmt/Makefile @@ -0,0 +1,2 @@ +datafmt.ps: datafmt.ms + dformat $< | pic | tbl | groff -ms -Tps >$@ diff --git a/doc/datafmt/datafmt.ms b/doc/datafmt/datafmt.ms new file mode 100644 index 0000000..8714350 --- /dev/null +++ b/doc/datafmt/datafmt.ms @@ -0,0 +1,140 @@ +.TL +Data Frame Format for the CAN Gauge Interface +.AU +Sam Anthony +.AI +.LP +The Gauge Interface receives parameter values from other nodes in the vehicle via the CAN bus. +It also accepts frames from a host PC for calibration. +The format of these calibration, or +.I control , +frames are the subject of this document. +.NH 1 +Parameters +.LP +The Interface listens for 6 parameters on the bus: +.nr step -1 1 +.IP \n+[step]. +Tachometer +.IP \n+[step]. +Speedometer +.IP \n+[step]. +Analog 1 +.IP \n+[step]. +Analog 2 +.IP \n+[step]. +Analog 3 +.IP \n+[step]. +Analog 4 +.LP +Each of these parameters has an associated CAN ID and a calibration table; thus, there are 6 IDs and 6 tables. +The Interface listens for these IDs and uses the tables to lookup output signal values to drive he gauges. +Each table has 32 rows, each of which contains a key and a value. +The keys and values are each 32-bit unsigned integers. +Numbers are transmitted in big-endian order in frames' DATA FIELD. +.NH 1 +Frames +.LP +In addition to the parameter frames, there are two types of +.I control +frame: +.B "Table Control" , +and +.B "ID Control" . +.NH 2 +Table Control Frame +.LP +The Table Control Frame is used to read and write rows of the calibration tables. +It is an extended frame with DLC=8. +It may be either a DATA FRAME: to write to a table\(emor a REMOTE FRAME: to read from a table. +.PP +The Table Control Frame has extended ID +.B 12720XXh . +The LSB, +.I X , +inticates which table, and which row of the table, to read or modify. +The upper 3 bits of +.I X +indicate one of the 6 tables [0, 5]. +The lower 5 bits of +.I X +indicate one of the table's 32 rows [0, 31]. +.begin dformat +style bitwid 0.15 +Table Control ID + 28-8 12720h + 7-5 Table + 4-0 Row +.end +.LP +The DATA FIELD contains a row of the table. +The row is composed of two 32-bit unsigned integers: a key and a value. +They are transmitted in big-endian order. +.begin dformat +style bitwid 0.07 +style recspread 0 +Table Control DATA FIELD + 7-0 D0 + 7-0 D1 + 7-0 D2 + 7-0 D3 + 7-0 D4 + 7-0 D5 + 7-0 D6 + 7-0 D7 +noname + 31-0 Key + 31-0 Val +.end +.LP +Upon receiving a Table Control DATA FRAME, the Interface will write the key and value to the row of the table specified in the ID. +.PP +In the case of a REMOTE FRAME, the Interface will read the row of the table specified in the ID, and respond with a DATA FRAME containing the key and value of the row. +.NH 2 +ID Control Frame +.LP +The ID Control Frame is used to read or modify the CAN ID associated with one of the 6 parameters. +It is an extended frame with DLC=8. +It may be either a DATA FRAME: to modify\(emor a REMOTE FRAME to read. +.PP +The ID Control Frame has extended ID +.B 127210Xh . +The least significant nibble, +.I X , +indicates one of the 6 parameters [0, 5]. +.begin dformat +style bitwid 0.15 +ID Control ID + 28-4 127210h + 3-0 X +.end +.LP +The DATA FIELD contains the CAN ID of the parameter specified in +.I X . +It may be either a standard or an extended ID. +In the case of a standard 11-bit ID, DLC=2 and the ID is sent as a 16-bit number. +In the case of an extended 29-bit ID, DLC=4 and the ID is sent as a 32-bit number. +The numbers are sent big-endian in both cases. +DLC can be used to determine whether the ID is standard or extended. +.begin dformat +style bitwid 0.08 +style recspread 0 +ID Control DATA FIELD (11-bit Std. ID) + 7-0 D0 + 7-0 D1 +noname + 15-11 + 10-0 Std. ID +.end +.begin dformat +style bitwid 0.08 +style recspread 0 +ID Control DATA FIELD (29-bit Ext. ID) + 7-0 D0 + 7-0 D1 + 7-0 D2 + 7-0 D3 +noname + 31-29 + 28-0 Ext. ID +.end |