Emily Wilson / Mbed 2 deprecated ECE4180Lab1

4180 lab 1

Dependencies:   mbed MCP23S17 PinDetect USBDevice

assembly_ec.s@12:cc5bda248946, 2020-01-22 (annotated)

Committer:
emilywilson
Date:
Wed Jan 22 13:08:48 2020 +0000
Revision:
12:cc5bda248946
Parent:
7:b7720a8623b5 
mouse extra credit and power management extra credit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilywilson 7:b7720a8623b5 1 // AREA asm_func, CODE, READONLY
emilywilson 7:b7720a8623b5 2 //; Export my_asm function location so that C compiler can find it and link
emilywilson 7:b7720a8623b5 3 // EXPORT assembly_ec
emilywilson 7:b7720a8623b5 4 //assembly_ec
emilywilson 7:b7720a8623b5 5 //;
emilywilson 7:b7720a8623b5 6 //; ARM Assembly language function to set LED1 bit to a value passed from C
emilywilson 7:b7720a8623b5 7 //; Pushbutton is on GPIO port 2.4 (connected to p22)
emilywilson 7:b7720a8623b5 8 //; Led is on GPIO port 2.0 (connected to p26)
emilywilson 7:b7720a8623b5 9 //; See Chapter 9 in the LPC1768 User Manual
emilywilson 7:b7720a8623b5 10 //; for all of the GPIO register info and addresses
emilywilson 7:b7720a8623b5 11 //; Pinnames.h has the mbed modules pin port and bit connections
emilywilson 7:b7720a8623b5 12 //;
emilywilson 7:b7720a8623b5 13 //
emilywilson 7:b7720a8623b5 14 //; Load GPIO Port 2 base address in register R1
emilywilson 7:b7720a8623b5 15 // LDR R1, =0x2009C040 ; 0x2009C040 = GPIO port 2 base address
emilywilson 7:b7720a8623b5 16 //; Load value from pushbutton into register R0
emilywilson 7:b7720a8623b5 17 // LDR R0, R1
emilywilson 7:b7720a8623b5 18 //; Move bit mask in register R2 for bit 4 only
emilywilson 7:b7720a8623b5 19 // MOV.W R2, #0x000010 ; 0x000010 = 1<<4 all "0"s with a "1" in bit 4
emilywilson 7:b7720a8623b5 20 //; See if pushbutton is pressed
emilywilson 7:b7720a8623b5 21 // CMP R0, #0
emilywilson 7:b7720a8623b5 22 //; (If-Then-Else) on next two instructions using equal cond from the zero flag
emilywilson 7:b7720a8623b5 23 // ITE EQ
emilywilson 7:b7720a8623b5 24 //; STORE if EQ - clear led 1 port bit using GPIO FIOCLR register and mask
emilywilson 7:b7720a8623b5 25 // STREQ R2, [R1,#0x58] ; if==0, set LED1 bit
emilywilson 7:b7720a8623b5 26 //; STORE if NE - set led 1 port bit using GPIO FIOSET register and mask
emilywilson 7:b7720a8623b5 27 // STRNE R2, [R1,#0x5C] ; if==1, clear LED1 bit
emilywilson 7:b7720a8623b5 28 //; Return to C using link register (Branch indirect using LR - a return)
emilywilson 7:b7720a8623b5 29 // BX LR
emilywilson 7:b7720a8623b5 30 // END