U3741BM Datasheet, PDF (13/25 Pages) ATMEL Corporation – UHF ASK RECEIVER IC

Out1 (mC)
t1
t2
t3
t5
t4
t10
t7
U3741BM
DATA (U3741BM)
X
Serial bi–directional
X
data line
Receiver
on
Bit 1
(”1”)
(Startbit)
OFF Command
TSleep
Figure 19. Timing diagram of the OFF-command via Pin DATA
X
X
Startup mode
ENABLE
T_Doze
toff
T_Sleep
DATA (U3741BM)
X
X
Serial bi–directional
data line
X
X
Receiver on
Startup mode
Figure 20. Timing diagram of the OFF-command via Pin ENABLE
Configuration of the Receiver
The U3741BM receiver is configured via two 12-bit
RAM registers called OPMODE and LIMIT. The
registers can be programmed by means of the
bi-directional DATA port. If the register contents have
changed due to a voltage drop, this condition is indicated
by a certain output pattern called reset marker (RM). The
receiver must be reprogrammed in that case. After a
power-on reset (POR), the registers are set to default
mode. If the receiver is operated in default mode, there is
no need to program the registers.
Table 3 shows the structure of the registers. According to
table 2, bit 1 defines if the receiver is set back to polling
mode via the OFF command, (see chapter ‘Receiving
Mode’) or if it is programmed. Bit 2 represents the
register address. It selects the appropriate register to be
programmed.
Table 2. Effect of Bit 1 and Bit 2 in programming the registers
Bit 1 Bit 2
Action
1 x The receiver is set back to polling
mode (OFF command)
0 1 The OPMODE register is programmed
0 0 The LIMIT register is programmed
Table 4 and the following illustrate the effect of the indi-
vidual configuration words. The default configuration is
highlighted for each word.
BR_Range sets the appropriate baud rate range. At the
same time it defines XLim. XLim is used to define the
bitcheck limits T_{Lim_min} and T_{Lim_max} as shown in
table 4.
POUT can be used to control the sensitivity of the
receiver. In that application, POUT is set to 1 to reduce the
sensitivity. This implies that the receiver operates with
full sensitivity after a POR.
Rev. A1, 15-Oct-98
Preliminary Information
13 (25)