Datasheet

119
AT89C51IC2
4301D–8051–02/08
Autobaud Performances 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 AT89C51IC2 to
establish the baud rate. Table 91 shows the autobaud capability.
Command Data Stream
Protocol
All commands are sent using the same flow. Each frame sent by the host is echoed by
the bootloader.
Table 91. Autobaud Performances
Frequency (MHz)
Baudrate (bit/s) 1.8432 2 2.4576 3 3.6864 4 5 6 7.3728 8
2400 OK OK OK OK OK OK OK OK OK OK
4800 OK - OK OK OK OK OK OK OK OK
9600 OK - OK OK OK OK OK OK OK OK
19200 OK - OK OK OK - - OK OK OK
38400 - - OK OK - OK OK OK
57600 - - - - OK - - - OK
115200 - - - - - - - - OK
Frequency (MHz)
Baudrate (bit/s) 10 11.0592 12 14.318 14.746 16 20 24 26.6
2400 OK OK OK OK OK OK OK OK OK
4800 OK OK OK OK OK OK OK OK OK
9600 OK OK OK OK OK OK OK OK OK
19200 OK OK OK OK OK OK OK OK OK
38400 - OK OK OK OK OK OK OK OK
57600 - OK - OK OK OK OK OK OK
115200 - OK - OK OK - - - -