This example repeats the Prutimer example that used the cycle counter.
This example uses the IEP timer.
Code at: https://github.com/jstampfl/Prutimer_IEP
/ pi.p
// To get the echo pulse on pin P8 15.
// assemble: pasm -v3 -b pt.p (could be pasm_2 if you follow
directions )
.setcallreg r2.w0 //
.origin 0
.entrypoint T811
#define CTRL 0x22000 //Start of control registers.
#define IEP 0x2E000 //Start of IEP registers.
T811:
ldi r11,0
ldi r12,0 //pointer to data memory
mov r7, 0x111 // value to enable the IEP
// GLOBAL_CONFIG
// 0x1 to enable
// 0x10 to set default increment
// 0x100 to set compensation increment
// compensation is not used here
mov r5,IEP // pointer to IEP registers
ldi r6,0 // index for IEP registers
ldi r3, 0 // zero to disable IEP
sbbo r3,r5,r6,4 // Disable the IEP count
ldi r6,0xC // Offset for IEP counter
ldi r4,1
sbbo r4,r5,r6,4 // zero the counter
TB1:
qbbs TB1,r31,15 // wait here for echo line to go low
// WAIT FOR THE ECHO PULSE
TB2:
qbbc TB2,r31,15 // wait here for echo line to go high
// - start of pulse
// START THE IEP COUNTER
sbbo r7,r5,0,4 // enable IEP
// WAIT FOR THE PULSE TO END
TB3:
qbbs TB3,r31,15 // wait here until echo line goes low.
// GET THE CYCLE COUNT AND PUT IN PRU0 LOCAL DATA MEMORY
lbbo r11,r5,0xC,4 // get the count
sbbo r10,r12,0,8 // put r10 & r11 (the unused signal
// & cycle count) in pru0 data memory
// STOP THE IEP COUNTER
sbbo r3,r5,0,4 // put back
sbbo r3,r5,0xC,4 // Zero the cycle count
// SEND INTERRUPT SIGNAL TO LINUX SIDE
mov r31.b0,35 //Send interrupt to Linux side
lbbo r11,r12,8,4 // Check for end flag from Linux side
qbne TB1,r11,2 // go back for more
TB4:
halt
--
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