Övning 7. Timer, serieport

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1 Övning 7 Timer, serieport

2 7.6 timer_1 Memory-Mapped addresses 0x920 status 0x924 control 0x928 periodl 0x92C periodh 0x930 snapl 0x934 snaph 15 0 Run TO (Time-Out) ITO cont start stop

3 timer_1 start D Q cl Q run stop 50 MHz clock write from program load -1 copy period copy counter snap-shot read from program zero D cl set Q Q clear from program read from program time-out

4 snaptime volatile int * const timer_1_base = ( (volatile int *) 0x920 ); unsigned int snaptime( void ) { unsigned int snaphigh; unsigned int snaplow; unsigned int snap; } timer_1_base[ 4 ] = 0; snaphigh = timer_1_base[ 5 ] & 0xffff; snaplow = timer_1_base[ 4 ] & 0xffff; snap = (snaphigh << 16) snaplow; return( snap );

5 7.1a Seriell kommunikation Bit för bit i stället för alla på en gång Sändare parallella data in skiftregister seriell kabel skiftregister parallella data ut Mottagare

6 7.1b Synkron seriell kommunikation Klocksignalen överförs på en extrasladd Synkroniseringskoder skickas då och då så att skiftregistren börjar på samma bit clock seriell kabel klocksignal clock

7 7.1b Asynkron seriell överföring Avkänningstidpunkter 0 x x x x x x x P bitars ASCII en startbit (0) en Paritetsbit (P) Stoppbit(ar) (1:or) Synkroniseringsflank övergång från 1:a till 0:a

8 7.1 Tecknet '&' = 0x26 0x26 med 7 binära bitar = minst signifikant bit sänds först P = 1 så att vi får jämnt antal 1:or totalt bitars ASCII en startbit (0) en Paritetsbit (P) Stoppbit(ar) (1:or) Synkroniseringsflank övergång från 1:a till 0:a

9 7.1g Olika bitfrekvens hos sändare och mottagare Rätt hastighet -12 V (1) +12 V (0) -12 V (1) avkänningstidpunk ter Om mottagaren är lite för snabb +12 V (0)

10 7.2 Serieport i nios2 RxDATA (RD) uart_0 0x860 0x864 0x868 TxDATA (WR) STATUS RxRdy (IBF) TxRdy (OBE) läsning av RxDATA nollställer IBF skrivning till TxDATA nollställer OBE

11 7.3 Eko.text.align 2.global main main: call in_char # get character from keyboard mov r4,r2 # copy return-value to parameter call out_char # send to screen br main # do it again

12 Eko i C int in_char( void ); /* Extern funktion "importeras". */ void out_char( int ); /* Extern funktion "importeras". */ int main( void ) { int c; while( 1 ) /* Oändlig slinga. */ { c = in_char(); /* Vänta på tecken, läs ett. */ out_char( c ); /* Skriv tecknet till serieport. */ } }

13 7.3 Eko: in_char.equ uart_0,0x860.equ uart_rxrdybitmask,0x80.text.align 2.global in_char in_char: movia r8,uart_0 # set uart_0 address ldw r9,8(r8) # get uart_0 status andi r9,r9,uart_rxrdybitmask# check RxRdy bit beq r9,r0,in_char # wait if nothing new ldw r2,0(r8) # get new data, and clear RxRdy andi r2,r2,0xff # clear unspecified bits from ser-port ret # return to caller

14 7.3 Eko: out_char Nästan som in_char men inte riktigt.equ uart_0,0x860.equ uart_txrdybitmask,0x40.text.align 2.global out_char out_char: movia r8,uart_0 # set uart_0 address ldw r9,8(r8) # get uart_0 status andi r9,r9,uart_txrdybitmask # check TxRdy bit beq r9,r0,out_char # wait if busy stw r4,4(r8) # send new data ret # return to caller

15 out_char i C volatile unsigned int * const uart0 = (volatile unsigned int *) 0x860; #define UART_RECEIVE_BIT (0x80) /* RXRDY */ #define UART_TRANSMIT_BIT (0x40) /* TXRDY */ void out_char( int c ) { unsigned int tmp = 0; while( 0 == tmp ) { tmp = uart0[ 2 ] & UART_TRANSMIT_BIT; } uart0[ 1 ] = c & 0xff; }

16 in_char i C volatile unsigned int * const uart0 = (volatile unsigned int *) 0x860; #define UART_RECEIVE_BIT (1<<7) /* RXRDY */ #define UART_TRANSMIT_BIT (1<<6) /* TXRDY */ int in_char( void ) { while( 0 == (uart0[ 2 ] & UART_RECEIVE_BIT) ); return( uart0[ 0 ] & 0xff ); }

17 7.5 in_charx non-blocking input.text.align 2.global in_charx in_charx: movi r2,-1 # set return value for no-input case movia r8,uart_0 # set uart_0 address ldw r9,8(r8) # get uart_0 status andi r9,r9,uart_rxrdybitmask # check RxRdy bit beq r9,r0,endg # return if nothing new ldw r9,0(r8) # get new data andi r2,r9,0xff # tidy up input data endg: ret # return to caller

18 in_charx i C volatile unsigned int * const uart0 = (volatile unsigned int *) 0x860; #define UART_RECEIVE_BIT (1<<7) /* RXRDY */ #define UART_TRANSMIT_BIT (1<<6) /* TXRDY */ int in_char( void ) { /* Pre-load return value in case nothing new arrived. */ int r = -1; } if(uart0[2] & UART_RECEIVE_BIT) r = uart0[0] & 0xff; return( r );

19 in_charx i C volatile unsigned int * const uart0 = (volatile unsigned int *) 0x860; #define UART_RECEIVE_BIT (0x80) /* RXRDY, bit 7 */ #define UART_TRANSMIT_BIT (0x40) /* TXRDY, bit 6 */ int in_charx( void ) { } unsigned int tmp = uart0[ 2 ] & UART_RECEIVE_BIT; if( tmp ) return( uart0[ 0 ] & 0xff ); else return( -1 );

20 7.5 out_charx, non-blocking output.texṭ align 2.global out_charx out_charx: movi r2,-1 # set return value for busy case movia r8,uart_0 # set uart_0 address ldw r9,8(r8) # get uart_0 status andi r9,r9,uart_txrdybitmask # check TxRdy bit beq r9,r0,endp # return if busy stw r4,4(r8) # send data movi r2,1 # reset return value, indicates success endp: ret # return to caller

21 7.5 Eko non-blocking version.data.align 2.text.global main main: call in_charx # anything new? blt r2,r0,main # if not, wait mov r4,r2 # copy input to parameter put: push r4 # save r4 call out_charx # try to send pop r4 # restore r4 blt r2,r0,put # if transmitter busy, wait br main

22 7.6 Korsvis kommunikation Ena labbgruppen putty DE2 Andra labbgruppen putty DE2

23 7.6 Korsvis kommunikation Nya subrutiner behövs rec_charx START check_timer. tick, puttime send_char in_charx? NEJ rec_charx som in_charx men för annan serieport JA send_char send_char som out_char men för annan serieport rec_charx? NEJ send_char, out_char: blocking JA väntan blir högst 100 μs out_char

24 7.6 send_char volatile int * uart1_receive = (volatile int *) 0x880; volatile int * uart1_send = (volatile int *) 0x884; volatile int * uart1_status = (volatile int *) 0x888; #define UART_TRANSMIT_BIT (1 << 6) void send_char( int c ) { int status_check = 0; while( 0 == status_check ) status_check = *uart1_status & UART_TRANSMIT_BIT; } *uart1_send = c & 0xff;

25 7.6 rec_charx volatile int * uart1_receive = (volatile int *) 0x880; volatile int * uart1_send = (volatile int *) 0x884; volatile int * uart1_status = (volatile int *) 0x888; int rec_charx( void ) { /* Pre-load return value in case nothing new arrived. */ int returnvalue = -1; /* If RxRdy status bit is set, read new input. */ if( *uart1_status & 0x80 ) returnvalue = *uart1_receive & 0xff; } return( returnvalue ); /* Return to caller. */