PGA450-Q1_14 Datasheet, PDF (44/61 Pages) Texas Instruments – ULTRASONIC-SENSOR SIGNAL CONDITIONER

PGA450-Q1
SLDS185A – APRIL 2012 – REVISED APRIL 2012
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LIN Slave Protocol Rx
If the PID field corresponds to an Rx message, the following are the steps to receive a LIN message.
In the PID interrupt service routine, do the following:
• Load DATA_CNT ESFR with the expected number of Rx data bytes.
• Set the RX_TX bit in LIN_CTRL ESFR to 0 to Rx a message.
In the Rx interrupt service routine, do the following:
• Transfer data from the RX_DATA buffers to RAM.
See the Programmer's Guide (SLDU006) for details on the ESFRs.
LIN Slave Protocol Tx
If the PID field corresponds to a Tx message, the following are the steps to receive a LIN message.
In the PID interrupt service routine, do the following:
• Load DATA_CNT ESFR with the number of data bytes to be transmitted.
• Load TX_DATA buffers with the data that is to be transmitted.
• Set the RX_TX bit in LIN_CTRL ESFR to 1 to Tx a message.
In the Tx interrupt service routine, do the following:
• User specific
See the Programmer's Guide (SLDU006) for details on the ESFRs.
NOTE
The LIN PID will be received and stored in the LIN_PID ESFR. This register will be
cleared when the LIN message transmission/reception is complete. Therefore, to retain
the value of the LIN_PID, the user has to copy the value of the ESFR to a RAM variable.
LIN Slave Status
The PGA450-Q1 has a LIN status register (LIN_STATUS) register that has the error status of the received LIN
frame.
This LIN_STATUS register can be cleared at any time by setting the CLR_ERR bit in the LIN_CFG register to 1.
LIN Slave Framing Error Status
The LIN_STATUS register in the PGA450-Q1 has the following bits that reflect any framing errors in the received
LIN message:
• CHECKSUM: This bit is set to 1 if the received checksum does not match the calculated checksum.
• PARITY: This bit is set to 1 if the received PID has a parity error.
• STOP_BIT_VAL: This bit is set to 1 if the LIN bus does not go high for a stop bit right after the 8th data bit is
received/transmitted. This check is done at the end of the PID field of each Tx and Rx data byte.
LIN Slave Timing Error Status
The LIN_STATUS register in the PGA450-Q1 has bits that reflect any LIN timing errors in the received LIN
message. The timing errors are based on the diagram show in Figure 36.
Table 15 describes the various timing errors in the received LIN message that are detected by the PGA450-Q1.
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