maxq7667 Maxim Integrated Products, Inc., maxq7667 Datasheet - Page 29

• Manufacturer Part Number: maxq7667
• Description: 16-bit, Risc, Microcontroller-based, Ultrasonic Distance-measuring System
• Manufacturer: Maxim Integrated Products, Inc.

the application code executes. The application codes
initiate reprogramming. If the password is not set, the
MAXQ7667 monitors the UART for an autobaud char-
acter (0x0D). If this character is received, the device
sets its serial baud rate and initiates a boot loader pro-
cedure. If 0x0D is not received after five seconds, the
device begins execution of the application code.
The following bootloader functions are supported:
The in-application programming feature allows the µC
to modify its own flash program memory while simulta-
neously executing its application software. This allows
on the fly software updates in mission-critical applica-
tions that cannot afford downtime. Erase and program
the flash memory using the flash programming func-
tions in the utility ROM. Refer to Section 18 of the
MAXQ7667 User’s Guide for a detailed description of
the utility ROM functions.
Power consumption reaches its minimum in stop mode
(STOP = 1). In this mode, the external oscillator, inter-
nal RC oscillator, system clock, and all processing
halts. Trigger an enabled external interrupt input or
directly apply an external reset on RESET to exit stop
mode. Upon exiting stop mode, the µC either waits for
the external high-frequency crystal to complete its
warmup period or starts execution immediately from its
internal RC oscillator while the crystal warms up.
Multiple interrupt sources quickly respond to internal
and external events. The MAXQ architecture uses a
single interrupt vector (IV) and single interrupt-service
routine (ISR) design. Enable interrupts globally,
• Load
• Dump
• CRC
• Verify
• Erase
______________________________________________________________________________________
Ultrasonic Distance-Measuring System
In-Application Programming
16-Bit, RISC, Microcontroller-Based,
Stop Mode
Interrupts
individually, or by module. When an interrupt condition
occurs, its individual flag is set even if the interrupt
source is disabled at the local, module, or global level.
Clear interrupt flags within the interrupt routine to avoid
repeated false interrupts from the same source.
Provide an adequate delay between the write to the
flag and the RETI instruction using application software
to allow time for the interrupt hardware to remove the
internal interrupt condition. Asynchronous interrupt
flags require a one-instruction delay and synchronous
interrupt flags require a two-instruction delay.
When an enabled interrupt is detected, software jumps
to a user-programmable interrupt vector location. The
IV register defaults to 0000h on reset or power-up.
Once software control transfers to the ISR, use the
interrupt identification register (IIR) to determine if the
source of the interrupt is a system register or peripheral
register. The specified module identifies the specific
interrupt source. The following interrupt sources are
available:
• Watchdog interrupt
• External interrupts 0–7 on port 0 and port 1
• Timer 0 low compare, low overflow, capture/com-
• Timer 1 low compare, low overflow, capture/com-
• Timer 2 low compare, low overflow, and overflow
• Schedule timer alarm interrupt
• SPI data transfer complete, mode fault, write colli-
• UART transmit, receive interrupts
• LIN mode master or slave interrupt
• SAR ADC data ready interrupt
• Echo envelope LPF output, FIFO full, and com-
• Digital and I/O voltage brownout interrupts
• High-frequency oscillator failure interrupt
pare, and overflow interrupts
pare, and overflow interrupts
interrupts
sion and receive overrun interrupts
parator interrupts
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