( File format: PDF, 858 Kbytes )
Mobile I/O Companion Supporting Key-Scan, I/O Expansion, PWM, and ACCESS.bus Host Interface
National Semiconductor
Description
The LM8322 Mobile I/O Companion is a dedicated device to unburden a host processor from scanning a matrix-addressed keypad. In addition, the LM8322 provides general-purpose I/O expansion, and PWM outputs useful for dynamic LED brightness modulation. It communicates with the host through an I 2C-compatible ACCESS.bus interface. An interrupt output is available for signaling key-press and key-release events. Communication frequencies up to 400 kHz (Fast-mode) bus speed are supported. The LM8322 supports a predefined set of commands. These commands enable a host device to keep control over all functions.
Features
Key Features
• Supports keypad matrices of up to 8 × 12 keys plus 8 special-function (SF) keys for a total of 104 keys. SF keys pull keypad scan inputs directly to ground, rather than connecting to a keypad scan output.
• Supports I 2C-compatible ACCESS.bus interface in slave mode up to 400 kHz (Fast-mode).
• Three host-programmable PWM outputs useful for smooth LED brightness modulation.
• Supports general-purpose I/O expansion on pins not otherwise used for keypad interface.
• Key-scan event storage in a FIFO buffer for up to 15 events.
• Key events, errors, and dedicated hardware interrupts request host service by asserting the ^IRQ output.
• The correct reception of a command may be assumed, if no error is reported from the LM8322 after receiving a command.
• Wake-up from Halt mode on any matrix key-scan event, any use of the SF keys, or any activity on the ACCESS.bus interface.
• Supports keypad matrices of up to 8 × 12 keys plus 8 special-function (SF) keys for a total of 104 keys. SF keys pull keypad scan inputs directly to ground, rather than connecting to a keypad scan output.
• Supports I 2C-compatible ACCESS.bus interface in slave mode up to 400 kHz (Fast-mode).
• Three host-programmable PWM outputs useful for smooth LED brightness modulation.
• Supports general-purpose I/O expansion on pins not otherwise used for keypad interface.
• Key-scan event storage in a FIFO buffer for up to 15 events.
• Key events, errors, and dedicated hardware interrupts request host service by asserting the ^IRQ output.
• The correct reception of a command may be assumed, if no error is reported from the LM8322 after receiving a command.
• Wake-up from Halt mode on any matrix key-scan event, any use of the SF keys, or any activity on the ACCESS.bus interface.
As the hyperlinked contents/websites are those of third parties, we cannot vouch for their accuracy or legitimacy.
Hot Articles
Most Popular Articles
Search EE Times India
Max's Cool Beans
Strange modes of transport and other "stuff"
Someone just pointed me at a YouTube video that claims to show the world's first e-powered multicopter flight...
