mc68hc908qz16 Freescale Semiconductor, Inc, mc68hc908qz16 Datasheet - Page 203

• Manufacturer Part Number: mc68hc908qz16
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

NF — Receiver Noise Flag Bit
FE — Receiver Framing Error Bit
PE — Receiver Parity Error Bit
15.8.5 ESCI Status Register 2
ESCI status register 2 (SCS2) contains flags to signal these conditions:
BKF — Break Flag Bit
RPF — Reception in Progress Flag Bit
Freescale Semiconductor
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.
This clearable, read-only bit is set when a logic 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.
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.
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This clearable, read-only bit is set when the ESCI detects a break character on the RxD pin. In SCS1,
the FE and SCRF bits are also set. In 9-bit character transmissions, the R8 bit in SCC3 is cleared. BKF
does not generate a CPU interrupt request. Clear BKF by reading SCS2 with BKF set and then reading
the SCDR. Once cleared, BKF can become set again only after logic 1s again appear on the RxD pin
followed by another break character. Reset clears the BKF bit.
This read-only bit is set when the receiver detects a logic 0 during the RT1 time period of the start bit
search. RPF does not generate an interrupt request. RPF is reset after the receiver detects false start
bits (usually from noise or a baud rate mismatch), or when the receiver detects an idle character.
Polling RPF before disabling the ESCI module or entering stop mode can show whether a reception is
in progress.
1 = Noise detected
0 = No noise detected
1 = Framing error detected
0 = No framing error detected
1 = Parity error detected
0 = No parity error detected
1 = Break character detected
0 = No break character detected
1 = Reception in progress
0 = No reception in progress
Break character detected
Incoming data
Address:
Reset:
Read:
Write:
$0017
Bit 7
0
0
MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 4
Figure 15-15. ESCI Status Register 2 (SCS2)
= Unimplemented
6
0
0
5
0
0
4
0
0
3
0
0
2
0
0
BKF
1
0
Bit 0
RPF
0
I/O Registers
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