rp2da2.rp2dcc.dcc_rc_ch2.RComCmdRsp

class documentation

class RComCmdRsp(RailComRead):

Constructor: RComCmdRsp()

Channel 2 (Command Response) Decode

This runs on the command station. As there is only one DCC generator there can only be one of these too. It is a singleton class.

The channel 2 window is time from the start of the cutout. This is detected by monitoring the DRV8874 enable pin which is used to insert the cutout.

Datagram identifiers for channel 2 are defined in RCN-217 3.1 Table 6.

Class Method	`get_instance`	Get the RailCom ch2 detector instance.
Method	`__init__`	DCC Command object constructor.
Method	`get_dg_list`	Get Datagram list
Method	`get_dyn_chng`	get changes to dyn info
Method	`get_error_counts`	Get Error Counts
Method	`reset_stats`	Reset diagnostic information
Method	`set_last_command`	Set the last command
Constant	`DG_CDI`	current driving info - not specified yet
Constant	`DG_CV_AUTO`	Background CV transmission
Constant	`DG_DYN`	dynamic info (DG ID 7) datagram identifier.
Constant	`DG_EXT`	location information
Constant	`DG_POM`	POM response (CV value) datagram identifier.
Constant	`DG_TS1`	track search 1
Constant	`DG_TS14`	track search 14
Constant	`DG_TS2`	track search 2
Constant	`DG_XPOM10`	extended POM response - 3rd CV
Constant	`DG_XPOM11`	extended POM response - 4th CV
Constant	`DG_XPOM8`	extended POM response - 1st CV
Constant	`DG_XPOM9`	extended POM response - 2nd CV
Constant	`DYN_DIRECTION`	direction status byte
Constant	`DYN_REAL_SPEED`	real speed part 1 datagram identifier.
Constant	`DYN_REAL_SPEED1`	real speed part 2 datagram identifier.
Constant	`DYN_RECEP_STATS`	reception stats datagram identifier.
Constant	`DYN_TEMP`	decoder temperature
Constant	`DYN_TRACK_VOLT`	track voltage
Constant	`ERR_CODE`	list of error codes
Method	`_act_on_datagram`	Undocumented
Method	`_log_error`	Undocumented
Method	`_parse_cg2_msg`	Parse Channel 2 Message
Method	`_rail_com_msg`	Process RailCom Channel 2 response
Class Variable	`_rc_ch2`	Undocumented
Instance Variable	`_dgs`	Undocumented
Instance Variable	`_dyn_chng`	Undocumented
Instance Variable	`_dyn_info`	Undocumented
Instance Variable	`_errors`	Undocumented
Instance Variable	`_last_command`	Undocumented
Instance Variable	`_pom_acc`	Undocumented

@classmethod

def get_instance(cls): ¶

Get the RailCom ch2 detector instance.

This returns the singleton instance. It is instantiated on the first call.

Returns
The RailCom ch2 detector instance

def __init__(self): ¶

DCC Command object constructor.

The enable pin is that used to enable the DRV8874. It's set by the DCC generator PIO. It's monitored here by the PIO program as it's low going edge marks the start of the cutout.

The RailCom reader for channel 2 is instantiated and the base class is initiated.

Note

The RailCom reader will use two sequentially numbered state machines - the first is read from the hardware configuration.

The RailCom reader will use two sequentially numbered GPIO pins for receiving - the first is read from the hardware configuration.

The pin and state machine allocations are read from the hardware configuration.

def get_dg_list(self): ¶

Get Datagram list

Diagnostic method to retrieve the list of datagram types that have been decoded.

Returns
the set of datagram ids

def get_dyn_chng(self): ¶

get changes to dyn info

Returns
dyn info for first address in queue

def get_error_counts(self): ¶

Get Error Counts

Diagnostic method to retrieve the error counts for detected errors.

Returns
a dictionary of counts by error code.

def reset_stats(self): ¶

Reset diagnostic information

Clears the error counts and set of datagram ids.

def set_last_command(self, command): ¶

Set the last command

Used to set the command that will be used for interpreting the next channel 2 response message.

Parameters
command	The last serialised command object.

DG_CDI = ¶

current driving info - not specified yet

Value

const(4)

DG_CV_AUTO = ¶

Background CV transmission

Value

const(12)

DG_DYN = ¶

dynamic info (DG ID 7) datagram identifier.

Value

const(7)

DG_EXT = ¶

location information

Value

const(3)

DG_POM = ¶

POM response (CV value) datagram identifier.

Value

const(0)

DG_TS1 = ¶

track search 1

Value

const(1)

DG_TS14 = ¶

track search 14

Value

const(14)

DG_TS2 = ¶

track search 2

Value

const(2)

DG_XPOM10 = ¶

extended POM response - 3rd CV

Value

const(10)

DG_XPOM11 = ¶

extended POM response - 4th CV

Value

const(11)

DG_XPOM8 = ¶

extended POM response - 1st CV

Value

const(8)

DG_XPOM9 = ¶

extended POM response - 2nd CV

Value

const(9)

DYN_DIRECTION = ¶

direction status byte

Value

const(27)

DYN_REAL_SPEED = ¶

real speed part 1 datagram identifier.

Value

const(0)

DYN_REAL_SPEED1 = ¶

real speed part 2 datagram identifier.

Value

const(1)

DYN_RECEP_STATS = ¶

reception stats datagram identifier.

Value

const(7)

DYN_TEMP = ¶

decoder temperature

Value

const(26)

DYN_TRACK_VOLT = ¶

track voltage

Value

const(46)

ERR_CODE = ¶

list of error codes

Value

(RailComRead.ERR_WH, RailComRead.ERR_WL, RailComRead.ERR_OE)

def _act_on_datagram(self, datagram, addr): ¶

Undocumented

def _log_error(self, error_code): ¶

Undocumented

def _parse_cg2_msg(self): ¶

Parse Channel 2 Message

Inspect the message and extract datagrams which are saved in list and returned. The datagrams are tuples of (datagram id, payload). Bytes are either protocol control bytes, error bytes or data bytes. The least significant 6 bits of a data byte contrinbute to the payload of a datagram and the most significant 2 bits are ignored. The payload content of each byte is concatenated to form the datagram. The datagram id is the first 4 bits of the datagram. The datagram id is used to determine the length of the datagram.

def _rail_com_msg(self, last_command): ¶

Process RailCom Channel 2 response

This is called on termination of the RailCom Channel 2 message receipt window, when a response is detected. The addressed decoder returns a channel 2 message. Other mobile decoders remain silent.

It overrides the method in the base class. It runs in soft ISR context, being scheduled by the hard ISR.

Blank reads should have been intercepted in the hard ISR. They are not checked for here but should not be problematic.

Parameters
last_command	the command that initiated this response.

_rc_ch2 = ¶

Undocumented

_dgs: set = ¶

Undocumented

_dyn_chng = ¶

Undocumented

_dyn_info: dict = ¶

Undocumented

_errors: dict = ¶

Undocumented

_last_command = ¶

Undocumented

_pom_acc: dict = ¶

Undocumented