Rainbow Electronics ISD14B20 - Manual (Page 12)

ISD14B20
Publication Release Date: October 9, 2007
- 12 - Revision 0
LED
Mic+/-
or AnaIn
PlayE
SP+
SP-
REC
Norm/Mode
T
Deb
T
AHold
T
ASet
T
Settle1
T
Deb
T
EOM
T
Settle3
5.1.5. XCLK Feature
• When precision sampling frequency is required, external clock mode can be activated by setting XCLK
to Low. Under such condition, the resistor at Rosc pin must be removed and the external clock signal
must be applied to the Rosc pin. These conditions must be satisfied prior to any operations.
• However, when internal clock is used, XCLK must be linked to High.
• The external clock frequencies required for various sampling frequencies are listed in below table.
Sampling Freq [kHz] 12 8 6.4 5.3 4
XCLK [MHz]
3.072 2.048 1.638 1.356 1.024
5.2. D IRECT T RIGGER (
MODE
) O PERATION
• The direct trigger is selected by the MODE pin. Once chosen, the supply voltage must be reset to
allow the device to construct itself to the appropriate configuration by re-defining the function on the
related control pins. Also, the mode change is only allowed while the device is in power down state and
inhibited during an operation is in progress.
• Once direct trigger is activated, , & are utilized to select various (1 to 8) fixed
message configurations
FMC1 FMC2 FMC3
[1] . Pending upon the arrangement on , & FMC3 , each divided
message has approximate equal length of duration, which is related to the number of rows assigned as
in below table.
FMC1 FMC2
• The record or playback operation is pre-defined by the /P R pin. Setting this pin to Low allows record
operation while setting it to High enables playback operation.
• Each message can be randomly accessed via its message control pin ( M1 ~ M8 ) and the desired
operations are facilitated accordingly. Non-configured pins are automatically disabled and must be
floated.
Notes: [1] : Number of fixed message arrangement with respect to , & FMC3 . FMC1 FMC2
FMC3 FMC2 FMC1 # of fixed messages [1]
0 0 0 1
0 0 1 2
0 1 0 3