Rainbow Electronics RA01 - Manual (Page 12)

RA01
Version: 1.0 Date: 10/8/2008
Tel: +86-755-82973805 Fax: +86-755-82973550 E-mail: [email protected] http://www.hoperf.com 12
6. Low Battery Detector and Microcontroller Clock Divider Command
bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 POR
1 1 0 0 0 0 1 0 d2 d1 d0 elfc t3 t2 t1 t0 C213h
Bit 7-5 : Clock divider configuration (valid only if the crystal oscillator is on):
d2 d1 d0 Clock Output Frequency [MHz]
0 0 0 1
0 0 1 1.25
0 1 0 1.66
0 1 1 2
1 0 0 2.5
1 0 1 3.33
1 1 0 5
1 1 1 10
Bit 4 < elfc >: Enables low frequency (32 kHz) microcontroller output clock during sleep mode.
Bits 3-0 : Determines the threshold voltage of the threshold voltage V
lb
of the detector:
V
lb
= 2.0 V + T * 0.1 V
7. Data Filter Command
bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 POR
1 1 0 0 0 1 0 0 al ml dsfi sf ewi srt 1 0 C462h
Bit 7 < al >: Clock recovery (CR) auto lock control if set. It means that the CR start in fast mode after locking it
automatically switches to slow mode.
Bit 6 < ml >: Clock recovery lock control 1: fast mode, fast attack and fast release - 0: slow mode, slow attack and
slow release
Using the slower one requires more accurate bit timing (see Data Rate Command ).
Bit 5 < dsfi >: Disables autosleep on FIFO interrupt if set to 1.
Bit 4 <
sf >: Selects the type of the data filter:
sf Filter Type
0 Digital Filter
1 Analog Filter with external
capacitor on pin7
Digital: this is a digital realization of an analog RC filter followed by a comparator with hysteresis. The time constant
is automatically adjusted to the bit rate defined by the
Data Rate Command .
The table shows the optimal filter capacitor values for different data rates
4.8 kbps 9.6 kbps 19.2 kbps 38.4 kbps
6.8 nF 3.3 nF 1.5 nF 680 pF
Note: If analog RC filter is selected the internal clock recovery circuit and the FIFO can not be used.
Bit 3 < ewi >: Enables the automatic wake-up on any interrupt event.
Bit 2 : Resets the bit slicer capacitor.