HD64570 Datasheet, PDF (132/469 Pages) Hitachi Semiconductor – Serial Communications Adaptor

Bit 7 (NRZFM: NRZ/FM Select): Used in conjunction with the CODE1−CODE0 bits (below) to
specify the transmission code type (NRZ or FM). This bit specifies MSCI decoding and encoding
types. Only the NRZ type is available in asynchronous mode.
• Asynchronous mode
Reserved. This bit always reads 0 and must be set to 0.
• Byte synchronous/Bit synchronous mode
NRZFM = 0: Specifies NRZ transmission code type
NRZFM = 1: Specifies FM transmission code type
Bits 6−5 (CODE1−CODE0: Transmission Code Type): Used in conjunction with the NRZFM
bit (above) to specify the transmission/reception signal decoding and encoding type. Only the
NRZ type is available in asynchronous mode.
• Asynchronous mode
Reserved. These bits always read 0 and must be set to 0.
• Byte synchronous/Bit synchronous mode
NRZFM = 0: NRZ transmission code type
 CODE1, CODE0 = 0, 0: Specifies the NRZ transmission code type
 CODE1, CODE0 = 0, 1: Specifies the NRZI transmission code type
 CODE1, CODE0 = 1, 0: Reserved
 CODE1, CODE0 = 1, 1: Reserved
NRZFM = 1: FM transmission code type
 CODE1, CODE0 = 0, 0: Specifies the Manchester transmission code type
 CODE1, CODE0 = 0, 1: Specifies the FM1 transmission code type
 CODE1, CODE0 = 1, 0: Specifies the FM0 transmission code type
 CODE1, CODE0 = 1, 1: Reserved
Bits 4−3 (DRATE1−DRATE0: ADPLL Operating Clock/Bit Rate): Specify the ratio of the
ADPLL operating clock frequency to the bit rate in byte or bit synchronous mode.
• Asynchronous mode
Reserved. These bits always read 0 and must be set to 0.
• Byte synchronous/Bit synchronous mode
DRATE1, DRATE0 = 0, 0: ADPLL operating clock frequency = bit rate × 8
DRATE1, DRATE0 = 0, 1: ADPLL operating clock frequency = bit rate × 16
DRATE1, DRATE0 = 1, 0: ADPLL operating clock frequency = bit rate × 32
DRATE1, DRATE0 = 1, 1: Reserved
Bits 1−0 (CNCT1−CNCT0: Channel Connection): The functions of these bits are described
below.
Rev. 0, 07/98, page 116 of 453