P89V51RB2BBC datasheet(21/80 Pages) NXP

21 / 80 page

P89V51RB2_RC2_RD2_5

Product data sheet

Rev. 05 — 12 November 2009

21 of 80

NXP Semiconductors

P89V51RB2/RC2/RD2

8-bit microcontrollers with 80C51 core

A chip-erase operation can be performed using a commercially available parallel

programer. This operation will erase the contents of this boot block and it will be

necessary for the user to reprogram this boot block (block 1) with the NXP-provided

ISP/IAP code in order to use the ISP or IAP capabilities of this device. Go to

http://www.nxp.com/support for questions or to obtain the hex ﬁle for this device.

6.3.3 ISP

ISP is performed without removing the microcontroller from the system. The ISP facility

consists of a series of internal hardware resources coupled with internal ﬁrmware to

facilitate remote programming of the P89V51RB2/RC2/RD2 through the serial port. This

ﬁrmware is provided by NXP and embedded within each P89V51RB2/RC2/RD2 device.

The NXP 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 (VDD, VSS, TXD, RXD, and RST). Only a small connector

needs to be available to interface your application to an external circuit in order to use this

feature.

6.3.4 Using 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 P89V51RB2/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

P89V51RB2/RC2/RD2 will accept up to 32 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 32 (decimal). ISP commands

are summarized in Table 12. As a record is received by the P89V51RB2/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 P89V51RB2/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.

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