MAXQ3100-EMN+ MAXIM [Maxim Integrated Products], MAXQ3100-EMN+ Datasheet - Page 10

• Manufacturer Part Number: MAXQ3100-EMN+
• Description: Mixed-Signal Microcontroller with Analog Comparators, LCD, and RTC
• Manufacturer: MAXIM [Maxim Integrated Products]

Mixed-Signal Microcontroller with Analog
Comparators, LCD, and RTC
Following any reset, execution begins in the utility
ROM. The ROM software determines whether the pro-
gram execution should immediately jump to the start of
user-application code (located at address 0000h), or to
the bootloader. Routines within the utility ROM are user-
accessible and can be called as subroutines by the
application software. More information on the utility
ROM contents is contained in the user’s guide supple-
ment for this device.
Some applications require protection against unautho-
rized viewing of program code memory. For these
applications, access to in-system programming, in-
application programming, or in-circuit debugging func-
tions is prohibited until a password has been supplied.
A single password-lock (PWL) bit is implemented in the
SC register. When the PWL is set to one (power-on
reset default), 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 zero, these
utilities are fully accessible without the password. The
password is automatically set to all ones following a
mass erase.
The microcontroller’s EEPROM can be programmed by
two different methods: in-system programming and in-
application programming. Both methods afford great flex-
ibility in system design as well as reduce the life-cycle
cost of the embedded system. In-system programming
can be password protected to prevent unauthorized
access to code memory.
An internal bootloader allows the device to be reloaded
over a simple JTAG-compatible debug port. As a result,
system software can be upgraded in-system, eliminating
the need for a costly hardware retrofit when software
updates are required. Remote software uploads are pos-
sible that enable physically inaccessible applications to
be frequently updated. The interface hardware can be a
JTAG connection to another microcontroller, or a con-
nection to a PC serial port using a serial-to-JTAG con-
verter such as the one included in the MAXQ3100
evaluation kit. If in-system programmability is not
required, a commercial gang programmer can be used
for mass programming.
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In-System Programming
Programming
Activating the debug port and loading the test access
port (TAP) with the system programming instruction
invokes the bootloader. Setting the SPE bit to 1 during
reset through the debug port executes the bootloader-
mode program that resides in the utility ROM. When pro-
gramming is complete, the bootloader can clear the
SPE bit and reset the device, allowing the device to
bypass the utility ROM and begin execution of the appli-
cation software.
The following bootloader functions are supported:
• Load
• Dump
• CRC
• Verify
• Erase
The in-application programming feature allows the
microcontroller to modify its own program memory from
its application software. This allows on-the-fly software
updates in mission-critical applications that cannot
afford downtime. Alternatively, it allows the application
to develop custom loader software that can operate
under the control of the application software. The utility
ROM contains user-accessible programming functions
that erase and program memory. These functions are
described in detail in the user’s guide supplement for
this device.
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. Tables 1 and 4 show the MAXQ3100
register set.
In-Application Programming
Register Set