FX805J Ver la hoja de datos (PDF) - CML Microsystems Plc
Número de pieza
componentes Descripción
Fabricante
FX805J Datasheet PDF : 17 Pages
| |||
Controlling Protocol ......
“Read Status Register” – A/C 71 (79 ), followed by 1 byte of Reply Data.
H
H
The Status Register indicates the operational condition of the FX805. Bits 0 to 5 are set individually to indicate specific
actions within the device. When a Status Bit is set to a logic “1,” an Interrupt Request (IRQ) output is generated. A read of the
Status Register will reset the interrupt condition and ascertain the state of this register.
Table 4 (below) shows the conditions indicated by the Status Bits.
Status Bit
Set By
Logic
Cleared By
Logic
MSB
7,6
Received First
Not used
“0”
Not used
“0”
5
NRZ data transmission
“1”
1. Write to NRZ Tx Data Reg. or,
“0”
complete. No new data loaded.
2. General Reset or,
3. NRZ Encoder Powersave.
4
NRZ Tx Data Buffer ready for
“1”
1. Write to NRZ Tx Data Reg. or,
“0”
next data byte.
2. General Reset or,
3. NRZ Tx Powersave.
3
New NRZ Rx data received
“1”
1. Read NRZ Rx Data Reg. or,
“0”
before last byte was read.
2. General Reset or,
3. NRZ Decoder Powersave.
2
1 byte of NRZ Rx data
“1”
1. Read NRZ Rx Data Reg. or,
“0”
received.
2. General Reset or,
3. NRZ Decoder Powersave.
1
NOTONE Timer period expired.
“1”
1. Read Status Register or,
“0”
2. General Reset or,
3. CTCSS Decoder Powersave.
0
Rx Tone Measurement
“1”
1. Read Status Register or,
“0”
complete.
2. General Reset or,
3. CTCSS Decoder Powersave.
Table 4 Status Register
“Read CTCSS Rx Frequency Register” – A/C 72H(7AH), followed by 2 bytes of Reply Data.
Measurement of CTCSS Rx Frequency (fCTCSS IN)
The input sub-audio signal (fCTCSS IN), is filtered and
measured in the Frequency Counter over the “measurement
When the measurement period of a successful decode
is complete, the Rx Tone Measurement bit in the Status
period” (122.64ms).
Register, and the Interrupt bit are set.
The measuring function counts the number of complete
input cycles occurring within the measurement period and
then the number of measuring-clock cycles necessary to
make up the period.
The CTCSS Rx Frequency Register will now indicate
the sub-audio signal frequency (f
) in the form of 2
CTCSS IN
data bytes (1 and 0) as illustrated in Figure 6.
Complete
Input
Cycle
Measurement Period
Complete
Input
Cycle
Complete
Input
Cycle
Complete
Input
Cycle
Complete Measuring
Input
Clock
Cycle
Cycles
2 x f FILTERED and DOUBLED SUB-AUDIO INPUT SIGNAL
CTCSS IN
N
R
Fig.5 Measurement of a CTCSS Rx Frequency
8
Share Link: 