1 / 9

ECE 425

ECE 425. Pin Connect Block. Pin Limited. Processors tend to be severely pin limited. Way more functions available than is practical to connect individually to I/O pins. High-end packages may have over 1000 pins Difficult to manufacture boards for them. For “difficult,” read “expensive.”

telyn
Download Presentation

ECE 425

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. ECE 425 Pin Connect Block

  2. Pin Limited • Processors tend to be severely pin limited. • Way more functions available than is practical to connect individually to I/O pins. • High-end packages may have over 1000 pins • Difficult to manufacture boards for them. • For “difficult,” read “expensive.” • Inexpensive packages (like LPC2148 used in lab) have a small number of pins.

  3. Multi-Function Pins • Solution is to multiplex pin functions. • That’s always been done to some extent. • Example: Intel Address/Data Mux Bus, Motorola GPIO/Timer • ARM/LPC takes it much farther than 80’s architecture like 8051, HC12, etc. • Implication is that it may be impractical to use some modules simultaneously.

  4. Timer I/O • ARM timer needs to be able to read triggers from external world and send signals to external devices. • By default, timer is not connected to any pins. • Must be connected via Pin Connect Block. • This needs to be done before timer functions & interrupts are enabled. • Pins connected to timer functions then become unavailable for GPIO, etc.

  5. Pin Select Registers • Two 32-bit registers used to define functions that will be connected to pins. • Two bits per pin, up to 4 totally different uses for some pins. • Third control register primarily used to put I/O into debug/trace modes. • Most programmable pins default to GPIO. • Not all pins are programmable. VCC, Reset, etc.

  6. Pin Select 0 Register Snippet

  7. Pin Select Registers • Pin select addresses: • PINSEL0: 0xE002 C000 • PINSEL1 - 0xE002 C004 • Now still need to associate Px.y with something physical. • Look on pin diagram of device being used.

  8. Timer 0 Capture 0 • Connect it to a pin by writing binary 10 to bits 5:4 of Pin Select Register 0, address 0xE002_C000. • That would be 00000020h if all other bits are zeros • Then in the hardware design the input from the sensor is connected to Pin 22.

More Related