P89C51RB2BA datasheet(41/52 Pages) PHILIPS

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Philips Semiconductors

Preliminary specification

89C51RB2/89C51RC2/

89C51RD2

80C51 8-bit Flash microcontroller family

16KB/32KB/64KB ISP/IAP Flash with 512B/512B/1KB RAM

1999 Sep 23

+12 V OR + 5 V

+5 V

TxD

RxD

VSS

VPP

VCC

TxD

RxD

RST

XTAL2

XTAL1

SU01299

VSS

VCC

89C51RB2

89C51RC2

89C51RD2

Figure 44. In-System Programming with a Minimum of Pins

In-System Programming (ISP)

The In-System Programming (ISP) is performed without removing

the microcontroller from the system. The In-System Programming

(ISP) facility consists of a series of internal hardware resources

coupled with internal firmware to facilitate remote programming of

the 89C51RB2/RC2/RD2 through the serial port. This firmware is

provided by Philips and embedded within each

89C51RB2/RC2/RD2 device.

The Philips In-System Programming (ISP) facility has made in-circuit

programming in an embedded application possible with a minimum

of additional expense in components and circuit board area.

The ISP function uses five pins: TxD, RxD, VSS, VCC, and VPP (see

Figure 44). Only a small connector needs to be available to interface

your application to an external circuit in order to use this feature.

The VPP supply should be adequately decoupled and VPP not

allowed to exceed datasheet limits.

Using the In-System Programming (ISP)

The ISP feature allows for a wide range of baud rates to be used in

your application, independent of the oscillator frequency. 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 program 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 89C51RB2/RC2/RD2 to establish the baud rate. The ISP

firmware provides auto-echo of received characters.

Once baud rate initialization has been performed, the ISP firmware

will only accept Intel Hex-type records. Intel Hex records consist of

ASCII characters used to represent hexadecimal values and are

summarized below:

:NNAAAARRDD..DDCC<crlf>

In the Intel Hex record, the “NN” represents the number of data

bytes in the record. The 89C51RB2/RC2/RD2 will accept up to 16

(10H) data bytes. The “AAAA” string represents the address of the

first byte in the record. If there are zero bytes in the record, this field

is often set to 0000. The “RR” string indicates the record type. A

record type of “00” is a data record. A record type of “01” indicates

the end-of-file mark. In this application, additional record types will

be added to indicate either commands or data for the ISP facility.

The maximum number of data bytes in a record is limited to 16

(decimal). ISP commands are summarized in Table 8.

As a record is received by the 89C51RB2/RC2/RD2, the information

in the record is stored internally and a checksum calculation is

performed. The operation indicated by the record type is not

performed until the entire record has been received. Should an error

occur in the checksum, the 89C51RB2/RC2/RD2 will send an “X”

out the serial port indicating a checksum error. If the checksum

calculation is found to match the checksum in the record, then the

command will be executed. In most cases, successful reception of

the record will be indicated by transmitting a “.” character out the

serial port (displaying the contents of the internal program memory

is an exception).

In the case of a Data Record (record type 00), an additional check is

made. A “.” character will NOT be sent unless the record checksum

matched the calculated checksum and all of the bytes in the record

were successfully programmed. For a data record, an “X” indicates

that the checksum failed to match, and an “R” character indicates

that one of the bytes did not properly program. It is necessary to

send a type 02 record (specify oscillator frequency) to the

89C51RB2/RC2/RD2 before programming data.

The ISP facility was designed to that specific crystal frequencies

were not required in order to generate baud rates or time the

programming pulses. The user thus needs to provide the

89C51RB2/RC2/RD2 with information required to generate the

proper timing. Record type 02 is provided for this purpose.

WinISP, a software utility to implement ISP programming with a PC,

is available from Philips. Commercial serial ISP programmers are

available from third parties. Please check the Philips web site

(www.semiconductors.philips.com) for additional information.

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