CDC3205G-C Micronas, CDC3205G-C Datasheet - Page 180

• Manufacturer Part Number: CDC3205G-C
• Description: Automotive Controller Family The Device is a Microcontroller For Use in Automotive Applications.the On-chip Cpu is an Arm Processor ARM7TDMI with 32-bit Data And Address Bus, Which Supports Thumb format Instructions.
• Manufacturer: Micronas

CDC 32xxG-C
by the user. If after the transmission of this telegram the user
would like the next Tx-Tg in the CA to be sent, he deletes the
RSC flag. If he sets the RSC, then the transmit search starts
again at the beginning of the CA. The RSR flag has to be
deleted.
The set SR flag tells BI that this telegram is to be sent; SR
can be likened to a postage stamp. The TS flag must be
deleted before the CO is released with the deletion of LCK.
If the BI finds a CO whose SR flag has been set, it reserves
this (ACC = FALSE) and reports it ”ready to send”. It will be
transmitted as soon as no higher-priority telegrams occupy
the bus. After successful transmission, it deletes the flag SR
and sets TS. The setting of ACC re-releases the CO.
Whether an interrupt will be triggered depends on whether
CANxIDX in the GCS contains the value minus one (255)
and transmit interrupts are permitted.
The user should now reserve the CO, reset the flag TS and
delete CANxIDX so that other interrupts can also be
reported. Should he wish to send further data, he can now
enter this.
27.3.2.4. Receive Telegram
CM = Receive
With a receive telegram, data is received. If the EXF flag and
the unmasked bits of the identifier of a received telegram are
the same as those of a receive CO, the telegram will be cop-
ied to the CO. ID, DLC and data bytes are overwritten by the
received ID, DLC and data. Only as many data bytes as the
received DLC specify will be overwritten (max. 8). The DLC
actually received will be entered. A permitted receive CO is
only used when TS has been deleted or OW has been set.
Once a telegram has been received and copied to a CO, the
flag TS is set. An interrupt will also be initiated if receive
interrupts are permitted and CANxIDX contains the value
minus one (255).
If the user detects the reception of a telegram (TS set), he
must reserve the CO. Then he can read the data and, before
releasing the CO again, delete TS.
27.3.2.5. Receive All Telegrams
CM = Rx-All
If, while searching for an RX-CO, the BI comes across a free
Rx-All-CO, the received telegram will be entered here with-
out regard to ID and EXF.
Rx-All-COs should be applied at the end of the CA.
27.3.2.6. Fetch Telegram
CM = Fetch
A fetch CO is used to request data from another node. This is
done by sending a telegram with the identifier of the desired
data. The remote transmission request flag is set in this Tg.
No data is therefore sent with it. If another node has the
desired data available, this is transmitted with the same ID as
soon as bus traffic allows.
In this mode, only the reception of the data telegram can trig-
ger an interrupt.
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June 12, 2003; 6251-579-1PD
The sequence of a fetch cycle is represented for the user in
pseudo-code.
if (TS == FALSE && SR == FALSE)
The BI now transmits the telegram with the RTR flag set. The
other node receives the Tg, provides the data and returns
the telegram with RTR flag deleted. After the reply telegram
has been received, the BI sets the flag TS. The user waits for
the data.
/* wait for answer */
while (TS == FALSE) {/* do anything else */}
LCK = TRUE;
/* wait until BI released this CO */
while (ACC == FALSE) {/* do anything else */}
/* copy data */
TS = FALSE;
LCK = FALSE;
Instead of waiting for the answer, it is also possible for notifi-
cation to be given by a receive interrupt.
27.3.2.7. Provide Telegram
CM = Provide
A provide CO is used to prepare data for fetching. It is the
counterpart of a fetch CO. In a provide CO the RSR flag is
cleared. It will be set and deleted by the BI. The data can be
prepared in two ways:
In the first case, the user does not become active until a
remote frame has been received (Rx interrupt or polling from
RSR). After the CO has then been reserved, the data is writ-
ten, the SR flag is set and the CO is released. The BI
ensures then that the data is transferred back.
In the second case, the data has already been entered, SR
has been set and TS deleted before the request. When the
remote frame is received, the user does not need to become
active. Also, no Rx interrupt will be initiated. The data is sim-
ply fetched. In this case the requesting RTR telegram must
contain the correct DLC because, with an RTR telegram too,
a received DLC overwrites the local DLC.
In both cases a Tx interrupt can occur after the data telegram
has been transmitted.
27.3.2.8. Data Length Code
The data length code is 4 bits long. It can therefore contain
values between 0 and 15. In principle, no more than 8 bytes
can be transmitted. Empty data telegrams (DLC = 0) are also
possible.
If a telegram with a DLC greater than 8 is received, this value
will be written into the DLC of the CO, but exactly 8 bytes of
data will be copied.
If the DLC of a Tx-CO contains a value greater than 8, this
DLC will be transmitted, but only 8 bytes of data.
{
LCK = TRUE;
/* wait until BI released this CO */
while (ACC == FALSE) {/* do anything else */}
SR = TRUE;
TS = FALSE;
LCK = FALSE;
}
/* release CO */
/* claim CO */
PRELIMINARY DATA SHEET
/* send this Tg */
/* release CO */
/* claim CO */
/* CO is empty */
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