AS3900 datasheet(33/59 Pages) AMSCO

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AS3900

Data Sheet - Detail ed Description

ACP

Same as 5a, but in case the acp2 bit, REG 0x33<7> is set,

data transmission from the Master to the Clients is

possible. The address of the Client can be selected by the

sid2<2:0> bits in REG 0x33<6:4> that corresponds to the

timing unit (0-7) which has triggered the receive action. The

ACP code is sent with the appended 32 bit data from

error counter (cesX) for the according Client is cleared.

ACP

Same as 6a, but if the ACP is received, the data followed by the ACP

code is routed to dabuf register in REG 0x2F to 0x32 and the interrupt

acp_rtx is set (IRQ activated). The MCU can read the 32 bit ACP data

from register dabuf and decide what to do with. The communication

error counter (ces0) is cleared.

NAK

If the received Client ID is incorrect and/or the CRC is

wrong no dat_rtx interrupt is generated. The Master

switches to transmit mode and sends NAK (not-

acknowledge), if the number of narmax in REG 0x03<1:0>

is set to 0 the interrupt nak_rtx is set. The communication

error counter cesX in REG 0x14 to 0x17 is increased for

the according Client. If one Client exceeds the limit of the

communication error counter cesmax in REG 0x02<2:0>,

the affected timer is turned off in REG 0x01.

NAK or

Error

Same as 6a, if NAK is received, nak_rtx interrupt is generated (IRQ.is

set). The communication error counter ces0 is increased for this

Client in REG 0x14<2:0>.

Also in case there is response but data can not be identified it is

handled as NAK and the communication error counter ces0 is

increased.

NAR

If the Client ID matches with the expected ID the

synchronization pulse is sent to the related timer unit, but if

the CRC is wrong no dat_rtx interrupt is generated. The

Master switches to transmit mode and sends NAR (not-

acknowledge with re-transmit request), if the number of

NAR (re-transmits) is set to a non-zero value in register bits

narmax in REG 0x03<1:0>. The nar_sent interrupt is

generated for the MCU. The cesX counter is not changed.

The Master switches back to receive mode and waits for

data retransmission from the same Client.

NAR

Same as 6a, if NAR is received and narmax in REG 0x03<1:0> is

nonzero, a nar_rtx interrupt is generated, afterwards the transmit

mode is switched on and the old data is retransmitted. If narmax = 0

the interrupt nar_rtx is generated but no retransmit is initiated.

5d, 6d

NAR-

Repeat

NAK

During the retransmit the timer is not re synchronized

(initial synchronization is not changed due to re-transmit). If

the receive is successful ACK is sent. If there is CRC error

NAR is sent, if the number of consecutive retransmits does

not exceed the value in the narmax register. If this number

is exceeded, NAK is send instead of NAR and the

communication error counter cesX is increased for the

affected Client.

During the retransmit the timer is not re-synchronized (initial

synchronization is not changed due to retransmit). If the transmission

was successfully, ACK will be received and the current data

transmission is terminated (as in point 6a). If there was a CRC error

and narmax is not exceeded yet, another retransmit cycle is started. If

NAK is received the communication error counter ces0 is increased

Table 28. Communication

Step

Master

Client

AS3900 Datasheet(PDF) 33 Page - ams AG

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