MAXQ2010-RFX+ datasheet(23/34 Pages) MAXIM

23 / 34 page

16-Bit Mixed-Signal Microcontroller

with LCD Interface

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applications, access to in-system programming, in-

application programming, or in-circuit debugging func-

tions is prohibited until a password has been supplied.

The password is defined as the 16 words of physical

program memory at addresses 0010h to 001Fh.

A single password lock (PWL) bit is implemented in the

SC register. When the PWL is set to 1 (power-on reset

default) and the contents of the memory at addresses

0010h to 001Fh are any value other than all FFh or 00h,

the password is required to access the utility ROM,

including in-circuit debug and in-system programming

routines that allow reading or writing of internal memory.

When PWL is cleared to 0, these utilities are fully acces-

sible without the password. The password is automati-

cally set to all 1s following a mass erase.

Programming

The microcontroller’s flash memory can be pro-

grammed by two different methods: in-system program-

ming and in-application programming. Both methods

afford great flexibility in system design and reduce the

life-cycle cost of the embedded system. These features

can be password protected to prevent unauthorized

access to code memory.

(Bootloader) In-System Programming

An internal bootstrap loader allows the device to be

reloaded over a simple JTAG interface. As a result,

software can be upgraded in-system, eliminating the

need for a costly hardware retrofit when updates are

required. Remote software updates enable application

updates to physically inaccessible equipment. The

interface hardware can be a JTAG connection to anoth-

er microcontroller, or a connection to a PC serial port

using a serial-to-JTAG converter such as the MAXQJ-

TAG-001, available from Maxim. If in-system program-

mability is not required, use a commercial gang

programmer for mass programming.

Activating the JTAG interface and loading the test

access port (TAP) with the system programming

instruction invokes the bootstrap loader. Setting the SPE

bit to 1 during reset through the JTAG interface exe-

cutes the bootstrap-loader-mode program that resides

in the utility ROM. When programming is complete, the

bootstrap loader can clear the SPE bit and reset the

device, allowing the device to bypass the utility ROM

and begin execution of the application software.

The following bootstrap loader functions are supported:

• Load

• Verify

• Dump

• Erase

• CRC

In-Application Programming

The in-application programming feature allows the

microcontroller to modify its own flash program memory

while simultaneously executing its application software.

This allows on-the-fly software updates in mission-criti-

cal applications that cannot afford downtime.

Alternatively, it allows the application to develop cus-

tom loader software that can operate under the control

of the application software. The utility ROM contains

user-accessible flash programming functions that erase

and program flash memory. These functions are

described in detail in the

MAXQ Family User’s Guide:

MAXQ2010 Supplement.

Most functions of the device are controlled by sets of

registers. These registers provide a working space for

memory operations as well as configuring and address-

ing peripheral registers on the device. Registers are

divided into two major types: system registers and

peripheral registers. The common register set, also

known as the system registers, includes the ALU, accu-

mulator registers, data pointers, interrupt vectors and

control, and stack pointer. The peripheral registers

define additional functionality that may be included by

different products based on the MAXQ architecture.

This functionality is broken up into discrete modules so

that only the features required for a given product need

to be included.

The documentation on the module and register func-

tions is covered fully in the

MAXQ Family User’s Guide

and the

MAXQ Family User’s Guide: MAXQ2010

Supplement. This information includes the locations of

status and control bits and a detailed description of

their function and reset values. Refer to these docu-

ments for a complete understanding of the features and

operation of the microcontroller.

System Timing

For maximum versatility, the device can generate its

internal system clock from several sources:

• External clock source

• Internal oscillator using external crystal or resonator

• FLL using 32kHz clock source (approximately 8MHz)

• FLL with no external crystal (approximately 5MHz)

Operation from an external clock source or internal

oscillator using external crystal or resonator is similar to

other microcontrollers. The designer must remember

that the rated maximum speed of operation applies to

the speed of the microcontroller core, not the external

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