MC908GR32AVFAE Datasheet, PDF (172/314 Pages) Freescale Semiconductor, Inc – Microcontrollers

Enhanced Serial Communications Interface (ESCI) Module
NORMAL FLAG CLEARING SEQUENCE
BYTE 1
BYTE 2
BYTE 3
BYTE 4
READ SCS1
SCRF = 1
OR = 0
READ SCDR
BYTE 1
READ SCS1
SCRF = 1
OR = 0
READ SCDR
BYTE 2
READ SCS1
SCRF = 1
OR = 0
READ SCDR
BYTE 3
DELAYED FLAG CLEARING SEQUENCE
BYTE 1
BYTE 2
BYTE 3
BYTE 4
READ SCS1
SCRF = 1
OR = 0
READ SCDR
BYTE 1
READ SCS1
SCRF = 1
OR = 1
READ SCDR
BYTE 3
Figure 13-14. Flag Clearing Sequence
In applications that are subject to software latency or in which it is important to know which byte is lost
due to an overrun, the flag-clearing routine can check the OR bit in a second read of SCS1 after
reading the data register.
NF — Receiver Noise Flag Bit
This clearable, read-only bit is set when the ESCI detects noise on the RxD pin. NF generates an NF
CPU interrupt request if the NEIE bit in SCC3 is also set. Clear the NF bit by reading SCS1 and then
reading the SCDR. Reset clears the NF bit.
1 = Noise detected
0 = No noise detected
FE — Receiver Framing Error Bit
This clearable, read-only bit is set when a 0 is accepted as the stop bit. FE generates an ESCI error
CPU interrupt request if the FEIE bit in SCC3 also is set. Clear the FE bit by reading SCS1 with FE set
and then reading the SCDR. Reset clears the FE bit.
1 = Framing error detected
0 = No framing error detected
PE — Receiver Parity Error Bit
This clearable, read-only bit is set when the ESCI detects a parity error in incoming data. PE generates
a PE CPU interrupt request if the PEIE bit in SCC3 is also set. Clear the PE bit by reading SCS1 with
PE set and then reading the SCDR. Reset clears the PE bit.
1 = Parity error detected
0 = No parity error detected
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
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Freescale Semiconductor