QDC10 - Multiplex Data on Battery Power Lines
3.2
Transmit Mode
Transmission procedure is initiated by the host by a TxData or TxWakeData command followed by data
bytes. The device starts the transmission with an arbitration procedure used in order to detect and
resolve collisions on the channel. The arbitration procedure consists of a pattern of time slots, each
dedicated for transmission or for sensing of the DC-BUS. If the device senses a transmission during the
arbitration procedure it aborts the transmission. If the device succeeds to access the channel, the
device continues the transmission of a preamble sequence, followed by the rest of the coded message
and returns a TxAck to its host (which means that the transmission is over). If the device fails in
resolving the channel, it switches to Receive mode and receives a message (or RxError). If the device
does not return TxAck within 40mS, the Host (application) may wait a random period of time (to avoid
collisions) and send the message again to the device.
3.3
Receive Mode
Upon detection of a legal header, a message with a header and up to 16 data bytes will be received into
the device internal buffer. The device indicates the Host that a message is ready by raising the DataOut
signal. The Host has to read that message in 2mS to enable reception of a new message from the bus.
3.4
Sleep Mode
The Host can command the device to enter into sleep mode (e.g. when no signal is received or
transmitted for a time period defined by the application). The device wakes up every 18mS to detect
activity on the bus. A change on the DataIn signal will also wake-up the device. When the bus is
quiescent and the device needs to transmit a message to the bus, the Host has to send a TxWakeData
command. The TxWakeData command has a long preamble, to allow all other devices on the bus to
wake-up during the preamble and before the data is transmitted.
3.5
Controlling the QDC10
3.5.1
Data from Host to QDC10
The QDC10 device is controlled by a set of commands as listed in table 3.1. Data transmission starts
after the Host finishes to transfer the command byte and the data bytes into the QDC10 internal transmit
buffer.
3.5.2
Command Set
Host controls the QDC10 device with the following set of commands:
Table 3.1 - Command Set
Command
TxData
Code
Fxh
Description
Transmit the following 16-x bytes of data (2-16)
Transmit a long header followed by 16-x bytes of data
(2-16)
TxWakeData
8xh
Reset
Sleep
01h
02h
Restart the QDC10
QDC10 enter to Sleep mode
For the value of x - see table 3.3
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4
DS-QDC10 R1.5
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