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diff --git a/doc/calfmt/calfmt.ms b/doc/calfmt/calfmt.ms new file mode 100644 index 0000000..bd68732 --- /dev/null +++ b/doc/calfmt/calfmt.ms @@ -0,0 +1,214 @@ +.TL +User-Calibration CAN Frame Format +.AU +Sam Anthony +.AI +.LP +The Gauge Interface receives +.I signals +.[ +dbc10 +.] +from other nodes via the vehicle's CAN bus. +It also accepts frames from a host PC for calibration. +The formats of these calibration, or +.I control , +frames are the subject of this document. +.NH 1 +Signals +.LP +The Interface listens for 6 signals 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 signals has an associated CAN ID, encoding specification, and calibration table. +A signal's CAN ID specifies which message contains the signal. +It's encoding specification defines how the signal is encoded in the message's DATA FIELD. +And it's calibration field defines a mapping from the raw signal value extracted from the message to an output value that is used to generate a waveform to display the signal on a gauge. +.PP +Each table has 32 rows, each of which contains a key and a value. +The keys and values are 32-bit and 16-bit respectively. +Numbers are transmitted in big-endian order in frames' DATA FIELDs. +.NH 1 +Frames +.LP +In addition to the signal-carrying frames, there are also two types of +.I control +frame: +.B "Table Control" , +and +.B "Signal 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=6. +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 a 32-bit integer and a 16-bit integer: 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 +noname + 31-0 Key + 15-0 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 +Signal Control Frame +.LP +The Signal Control Frame is used to read or modify the CAN ID associated with one of the signals, as well as to read or modify the signal's encoding format. +It is an extended frame with DLC=7. +It may be either a DATA FRAME: to modify\(emor a REMOTE FRAME: to read. +.PP +Upon receiving a Signal Control DATA FRAME, the Interface will write the signal's new ID and encoding to the EEPROM. +Upon receiving a Signal Control REMOTE FRAME, the Interface will respond with a DATA FRAME containing the signal's ID and encoding which were retrieved from the EEPROM. +.PP +The ID Control Frame has extended ID +.B 127210Xh . +The least significant nibble, +.I X , +indicates one of the 6 signals [0, 5]. +.begin dformat +style bitwid 0.15 +Signal Control ID + 28-4 127210h + 3-0 X +.end +.LP +The DATA FIELD contains the signal's CAN ID and encoding format. +.begin dformat +style bitwid 0.08 +style recspread 0 +Signal Control DATA FIELD + 7-0 D0 + 7-0 D1 + 7-0 D2 + 7-0 D3 + 7-0 D4 + 7-0 D5 + 7-0 D6 +noname + 31-0 SigId + 23-0 Encoding +noname + 31 EXIDE + 30-29 Empty + 28-0 ID + 7-0 Start + 7-0 Size + 7 Order + 6 Sign + 5-0 Empty +.end +.LP +The signal's CAN ID is sent as a big-endian 32-bit integer in the +.I SigId +field. +The MSb\(embit 31, called +.I EXIDE \(em +indicates whether the ID is standard or extended. +.TS +tab(&); +Ci +L L. +EXIDE += 0 & Standard identifier += 1 & Extended identifier +.TE +The lower 11 or 29 bits hold the ID itself, depending on whether it is standard or extended. +In the case of a standard ID, +.I EXIDE =0 +and the ID is sent in the lower 11 bits of +.I SigId . +In the case of an extended ID, +.I EXIDE =1 +and the ID is sent in the lower 29 bits of +.I SigId . +.PP +The signal encoding defines how the signal's raw value is encoded in the message that carries it. +The encoding is sent in the +.I Encoding +field of the Signal Control Frame's DATA FIELD. +.LP +.I Start +specifies the position of the signal within the DATA FIELD of the message. +It corresponds to +.CW start_bit +in DBC. +.PP +.I Size +specifies the size of the signal in bits. +It corresponds to +.CW signal_size +in DBC. +.PP +.I Order +specifies the signal's byte order. +It corresponds to +.CW byte_order +in DBC. +.TS +tab(&); +Ci +L L. +Order += 0 & Big-endian += 1 & Little-endian +.TE +.LP +.I Sign +specifies the signal as being of type unsigned or signed. +It corresponds to +.CW value_type +in DBC. +.TS +tab(&); +Ci +L L. +Sign += 0 & Unsigned += 1 & Signed +.TE |