AT89C51ID2-SMSIM ATMEL [ATMEL Corporation], AT89C51ID2-SMSIM Datasheet - Page 129

• Manufacturer Part Number: AT89C51ID2-SMSIM
• Description: 8-bit Flash Microcontroller
• Manufacturer: ATMEL [ATMEL Corporation]

Flow Description
Overview
Communication Initialization
Autobaud Performances
Table 94. Autobaud Performances
4289A–8051–09/03
Frequency (MHz)
Baudrate (kHz)
2400
4800
9600
19200
38400
57600
115200
Frequency (MHz)
Baudrate (kHz)
2400
1.8432
8
OK
OK
OK
OK
OK
-
-
-
2
10
An initialization step must be performed after each Reset. After microcontroller reset,
the bootloader waits for an autobaud sequence ( see section ‘autobaud performance’).
When the communication is initialized the protocol depends on the record type
requested by the host.
FLIP, a software utility to implement ISP programming with a PC, is available from the
Atmel the web site.
The host initializes the communication by sending a ’U’ character to help the bootloader
to compute the baudrate (autobaud).
Figure 51. Initialization
The ISP feature allows a wide range of baud rates in the user application. It is also
adaptable to a wide range of oscillator frequencies. This is accomplished by measuring
the bit-time of a single bit in a received character. This information is then used to pro-
gram the baud rate in terms of timer counts based on the oscillator frequency. The ISP
feature requires that an initial character (an uppercase U) be sent to the AT89C51ID2 to
establish the baud rate. Table show the autobaud capability.
OK
OK
-
-
-
-
-
-
Communication opened
Init communication
Else
If (not received "U")
2.4576
11.0592
Host
OK
OK
OK
OK
OK
OK
-
-
3
12
OK
OK
OK
OK
OK
-
-
3.6864
14.746
OK
OK
OK
OK
OK
OK
OK
-
4
16
"U"
"U"
OK
OK
OK
OK
-
-
-
-
5
20
OK
OK
OK
OK
OK
-
-
-
Sends back U character
Performs autobaud
AT89C51ID2
6
24
Bootloader
OK
OK
OK
OK
OK
OK
-
-
7.3728
26.6
OK
OK
OK
OK
OK
OK
OK
OK
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