NEC UPD98413 User Manual page 72

(c) Address and control bytes check
Upon receiving a packet, the µ PD98413 detects the Address and control fields in the packet (first byte of the
POS packet) and checks it. If the value in the Address field of the packet is not FFh or the control field is not 03h,
the packet is handled as an address error packet, and the address error counter is incremented. The address
error packet is discarded internally, without being sent to the POS interface. If the address error does not occur,
µ PD98413 sends the packet stripped the address and control bytes or not stripped, which is the setting by the
ADRPAS bit of the MDPOSR register, to the POS interface.
The address and control error detection function is optional and it may be disabled by the ADRM bit of the
MDPOSR register.
(d) Packet size check
The µ PD98413 monitors the packets for both minimum and maximum size errors. The domain checked is only
an Information domain except address byte, control byte, and FCS. Each error is indicated by the interrupt and
the error counter. The packet size check function is optional and it may be disabled by the MDPOSR register.
Short size packet error
The µ PD98413 allows you to set the minimum receive packet size in the PRENR1 register. If receiving a packet
whose size is below the minimum, the µ PD98413 increments the short size packet counter and indicates it by the
interrupt. If receiving such a short size packet, the µ PD98413 outputs it as an error packet from the POS
interface. At the end of the packet, the RERR pin is asserted for notification. The Short packet size check
function, it may be disabled by the SPM bit of the MDPOSR register.
Long size packet error
The µ PD98413 allows you to set the maximum receive packet size in the PLENR2 register. Upon receiving a
packet whose size exceeds the maximum, the µ PD98413 increments the long size packet counter and indicates
it by the interrupt. Upon receiving such a long size packet, the µ PD98413 outputs it as an error packet from the
POS interface. At the end of the packet, the RERR pin is asserted for notification. The remaining data for the
packet exceeding the maximum is discarded internally. The Long packet size check function, it may be disabled
by the LPM bit of the MDPOSR register.
(e) Detection of abort packet
Upon receiving an abort packet (which ends with abort sequence 7D-7E), the µ PD98413 increments the receive
abort packet counter and indicates it by the interrupt. The received abort packet, which is stripped an abort
sequence (7D-7E), is output from the POS interface. At the end of the packet, the RERR pin is asserted for
notification.
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CHAPTER 3 FUNCTIONAL OUTLINE
PRELIMINARY
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