MAXQ610A-0000 MAXIM [Maxim Integrated Products], MAXQ610A-0000 Datasheet - Page 20

• Manufacturer Part Number: MAXQ610A-0000
• Description: 16-Bit Microcontroller with Infrared Module 1.70V to 3.6V Operating Voltage Range
• Manufacturer: MAXIM [Maxim Integrated Products]

16-Bit Microcontroller with Infrared Module
An external quartz crystal or a ceramic resonator can
be connected between HFXIN and HFXOUT on the
MAXQ610, as illustrated in Figure 9.
Noise at HFXIN and HFXOUT can adversely affect on-
chip clock timing. It is good design practice to place
the crystal and capacitors near the oscillator circuitry
and connect HFXIN and HFXOUT to ground with a
direct short trace. The typical values of external capaci-
tors vary with the type of crystal to be used and should
be initially selected based on the load capacitance as
suggested by the crystal manufacturer.
The MAXQ610 includes a ROM loader. The loader
denies access to the system, user loader, or user-appli-
cation memories unless an area-specific password is
provided. The ROM loader is not available in ROM-only
versions of the MAXQ610.
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 uploads are possible that
enable physically inaccessible applications to be fre-
quently 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 MAXQJTAG-001 available from
Maxim Integrated Products. If in-system programmabili-
Figure 9. On-Chip Oscillator
20
______________________________________________________________________________________
Loading Flash Memory
C1
On-Chip Oscillator
C2
ROM Loader
HFXIN
HFXOUT
V
DD
R
F
ty is not required, a commercial gang programmer can
be used for mass programming. Activating the JTAG
interface and loading the test access port (TAP) with
the system programming instruction invokes the boot-
strap loader. Setting the SPE bit to 1 during reset
through the JTAG interface executes 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.
In addition, the ROM loader also enforces the memory-
protection policies. 16-word passwords are required to
access the ROM loader interface.
Loading memory is not possible for ROM-only versions
of the MAXQ610 family.
From user-application code, flash can be programmed
using the ROM utility functions from either C or assem-
bly language. The function declarations that follow
show examples of some of the ROM utility functions
provided for in-application flash programming.
/* Write one 16-bit word to code address 'dest'.
* Dest must be aligned to 16 bits.
* Returns 0 = failure, 1 = OK.
*/
int flash_write (uint16_t dest, uint16_t data);
RF = 1MΩ ± 50%
C1 = C2 = 30pF
STOP
MAXQ610
CLOCK CIRCUIT
In-Application Flash
Programming