sm59d04g2 SyncMOS Technologies,Inc, sm59d04g2 Datasheet - Page 37

• Manufacturer Part Number: sm59d04g2
• Description: 8-bits Micro-controller 16kb+ Isp Flash & 1kb Ram Embedded
• Manufacturer: SyncMOS Technologies,Inc

When the master processor wants to transmit a block of data to one of several slaves, it first sends
out an address byte which identifies the target slave. An address byte differs from a data byte in that
the 9
a data byte. An address byte, however, will interrupt all slaves, so that each slave can examine the
received byte and see if it is being addressed. The addressed slave will clear its SM2 bit and
prepare to receive the data bytes that will be coming. The slave that weren’t being addressed leave
their SM2s set and go on their business, ignoring the coming data bytes.
SM2 has no effect in Mode 0, and in Mode 1 can be used to check the validity of the stop bit. In
Mode 1 reception, if SM2 = 1, the receive interrupt will not be activated unless a valid stop bit is
received.
10.2 Baud rates
The baud rate in Mode 0 is fixed:
Mode 0
is the value on reset), the baud rate is 1/32 the system frequency. If SMOD = 1, the baud rate is
1/16 the system frequency.
Mode 2
10.3 Using Timer 1 to Generate Baud Rates.
When Timer 1 is used as the baud rate generator, the baud rates in Modes 1 and 3 are determined
by the Timer 1 overflow rate and the value of SMOD as follows:
Modes 1 and 3
The Timer 1 interrupt should be disabled in this application. The timer itself can be configured for
either “timer” or “counter” operation, and in any of its 3 running modes. In the most typical
applications, it is configured for “timer” operation, in the auto-reload mode (high nibble of TMOD =
0010B). In that case, the baud rate is given by the formula
Modes 1 and 3
One can achieve very low baud rates with Timer 1 by leaving the Timer 1 interrupt enabled, and
configuring the timer to run as a 16-bit timer (high nibble of TMOD = 0001B), and using the Timer 1
interrupt to do a 16-bit software reload.
Specifications subject to change without notice contact your sales representatives for the most recent information.
ISSFD-M031
The baud rate in mode 2 depends on the value of bit SMOD in SFR PCON. If SMOD = 0 (which
th
bit is 1 in an address byte and 0 in a data byte. With SM2 = 1, no slave will be interrupted by
Baud Rate =
Baud Rate =
Baud Rate =
Baud Rate =
System
2
2
2
SMOD
SMOD
SMOD
32
32
32
×
×
× (System Frequency)
Frequency
(Timer 1 overflow rate)
System
6
6
×
[
256
Frequency
−
37
TH
] 1
16KB+ ISP Flash & 1KB RAM embedded
Ver.C SM59D04G2 07/2009
8-Bits Micro-controller
SM59D04G2