Example of reading data with PRUSS Uart.
Full code at: https://github.com/jstampfl/Pruuart
`
/ pu.p V1
// Use PRUSS uart to read data from ADAFRUIT Ultimate GPS
// reads data to nl, put in buffer and signal linux side.
.setcallreg r2.w0 // Going to use r31 for interrupt
.origin 0
.entrypoint TB
TB:
ldi r20,0
ldi r21,0
ldi r22,0
mov r0,0
sbbo r0,r20,r21,4
zero &r0,64 //zero 16 registers
TB05:
sbbo r0,r20,r21,64 //zero some of pru0 local memory
add r21,r21,64 // for linux string functions
add r22,r22,1
qbgt TB05,r22,20
TB1:
ldi r3,4 //Uart divisor =1250 = 0x04E2
sbco r3,c7,0x24,4 // 9600 at 16x
ldi r3,0xE2 //in DLL & DLH
sbco r3,c7,0x20,4
ldi r3,0x3 //LCR = 3, 8 none & 1
sbco r3,c7,0x0C,4 //
mov r3,0x6001 //Power &
sbco r3,c7,0x30,4 // = tx on, rx on & Free ot enable
ldi r4,0
ldi r5,0
ldi r3,0
ldi r20,0
ldi r21,0
TB2:
// r5 points to start of buffer
// r4 is offset into buffer
lbco r3,c7,0x14,4 //check LSR for date ready
qbbc TB2,r3.t0
lbco r3,c7,0,4 //data is ready, get from RBR
sbbo r3,r5,r4,1 // and put in buffer
add r4,r4,1
qbne TB2,r3,0xA // do until nl received
sbbo r20,r5,r4,1 // put null to terminate
ldi r4,0 // zero buffer pointer
mov r31.b0,35 // signal linux
jmp TB2
TB9:
mov r31.b0,35
ldi r4,0xFFFF
ldi r5,0
TB10:
add r5,r5,1
qbgt TB10,r5,r4
HALT
`