17_EEL4742-Notes#17 - EEL4742 Notes 17 Design an input port...

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EEL4742 Notes # 17 Design an input port at address FFFE Read operation from an input port Use octal Buffer 74LS244, = 0 ( select the output enable of cotal buffers) when: A0-A15 = FFFEh & VMA = 0 & R/W = 1 for Reading. Depending on the MSP 430, it can have between 2-6 I/O ports. These I/O ports in many cases are multifunction: Digital I/O or other function like the timer, A/D input or LED display. Ports are named using Px.y x= port #, y = the Bit for port x Each port has the following configuration: PXDIR 1 =output 0 = input, configures the direction of the Bit. 0 = usually default
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Unformatted text preview: PXSel 0 =digital I/O or 1 = other function . 0 = usually default PXRen 0 = pullup resistor disabled 1 = enabled PXIE enable interrupts for the port PXIN reads data from port x configured as input PXIN write data to port x configured as output Example: C program and Assembly program – to turn a LED on and off – delay between the 2 states In C program LED is located in Bit 1 using the MSP 430 small launchpad In Assembly program LED is located in Bit 2 using the MSP 430 Lab launchpad A In C: In Assembly:...
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  • Spring '11
  • Weeks
  • Assembly Language, Input/output, i/o ports, octal Buffer 74LS244

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