I'm using the Keil MCB900 eval board with a P89LPC938 at 7.3728MHz and the LPC900 development tools (demo version). I'm using most of Mark Odell's UART and Timer code.
I have setup Timer 1 as the baud rate generator and Timer 0 as a 10ms system timer tick. The timer tick toggles three LEDs at 10ms, 100ms, and 1s. Both the UART and Timer 0 have their own ISR (interrupt service routines) with the appropriate number and separate register banks. Each works fine on its own. But if I initialize both the timer tick AND the UART/Timer 1, it appears the timer tick runs wide open, or much faster than it should, as evidenced by the LEDs.
I have tried setting up different IP (interrupt priority) levels for each interrupt, but that doesn't seem to help. For now, they're both at level 0. Is there anything special (best practices, guidelines) you have to do to make multiple ISRs work?
Here is some of the code. I can post more.
volatile bit data Tick10ms; // 10ms volatile bit data Tick100ms; // 100ms volatile bit data Tick1s; // 1s static void Timer0_ISR(void) interrupt 1 using 2 { static U8 num10msTicks; TR0 = 0; // stop timer TL0 = TIMER0_10MS_LO; // reload TH0 = TIMER0_10MS_HI; TR0 = 1; // start timer Tick10ms = !Tick10ms; // 10ms ++num10msTicks; if (!(num10msTicks % 10)) { // 100ms Tick100ms = !Tick100ms; // toggle } if (num10msTicks == 100) { // 1s time region num10msTicks = 0; Tick1s = !Tick1s; // toggle } } static void uartIsr(void) interrupt 4 using 1 { static U8 data inChar; if (RI) { RI = 0; inChar = SBUF; if (s_rxRingEmpty || s_rxWrIdx != s_rxRdIdx) { s_rxRing[s_rxWrIdx] = inChar; ++s_rxWrIdx; #if RX_RING_SIZE != 256 s_rxWrIdx %= RX_RING_SIZE; #endif s_rxRingEmpty = 0; } } if (TI) { TI = 0; if (s_txRdIdx != s_txWrIdx) { SBUF = s_txRing[s_txRdIdx]; ++s_txRdIdx; #if TX_RING_SIZE != 256 s_txRdIdx %= TX_RING_SIZE; #endif } else { // declare empty after last SCON.TI event s_txRingEmpty = 1; } } } void main(void) { P2M1 = 0; // set output mode P1M1 = 0; TMR_Init(); // A initUart(BAUD_RATE_57600); // B EA = 1; // enable ints printf("Baud rate: 57600\n"); // B P2 = 0x00; // turn off LEDs while (1) { // endless loop LED0 = Tick10ms; // P2^0 LED1 = Tick100ms; // P2^1 LED2 = Tick1s; // P2^2 } }
I was initially looking for any guidelines or rules-of-thumb when running multiple ISRs. Anyway, here's more of it, including the one ISR with more comments:
#define XTAL_7_3728MHZ 7372800 // Common XTAL freqs #define XTAL_11_059MHZ 11059200 #define XTAL_FREQ XTAL_7_3728MHZ // our frequency #define TIMER_0_TICKS_PER_SEC (XTAL_FREQ/2) // 7372800/2 = 3686400 #define TIMER_0_TICKS_PER_MS (XTAL_FREQ/2)/1000 // 3686400/1000 = 3686.4 #define TIMER0_10MS (10 * TIMER_0_TICKS_PER_MS) // 36864 (0x7000) #define TIMER0_10MS_HI 65536 - ((U8) (TIMER0_10MS >> 8)) // reload values for 10ms #define TIMER0_10MS_LO 65536 - ((U8) TIMER0_10MS) #define TIMER0_INT_NUM 1 // interrupt #define UART_INT_NUM 4 // same as Odell's code #define SCON_8N1 0x40 // SCON.SM1 = 1, SM0,2 = 0 #define SCON_REN 0x10 // Timer 0 only #define TMOD_GATE_T0 0x08 #define TMOD_C_T_T0 0x04 #define TMOD_M1_T0 0x02 #define TMOD_M0_T0 0x01 #define T0_MODE_MASK (TMOD_GATE_T0 | TMOD_C_T_T0 | TMOD_M1_T0 | TMOD_M0_T0) #define T0_16BIT_TIMER (TMOD_M0_T0) // Timer 1 only #define TMOD_GATE_T1 0x80 #define TMOD_C_T_T1 0x40 #define TMOD_M1_T1 0x20 #define TMOD_M0_T1 0x10 #define T1_MODE_MASK (TMOD_GATE_T1 | TMOD_C_T_T1 | TMOD_M1_T1 | TMOD_M0_T1) #define T1_8BIT_AUTO_RELOAD (TMOD_M1_T1) #define PCON_SMOD 0x80 // Doubles baud rate timing of Timer 1 #define RX_RING_SIZE 32 // serial receive buffer size #define TX_RING_SIZE 32 // serial transmit buffer size // serial port tx/rx ring variables static U8 xdata s_rxRing[RX_RING_SIZE]; static U8 xdata s_txRing[TX_RING_SIZE]; static volatile bit data s_rxRingEmpty; static volatile bit data s_txRingEmpty; static volatile U8 data s_rxWrIdx; static volatile U8 data s_rxRdIdx; static volatile U8 data s_txWrIdx; static volatile U8 data s_txRdIdx; static UartBaudRates data s_currentBaudRate; static bit data s_translateEol; // \r into \r\n // timer tick variables volatile bit data Tick10ms; // 10ms volatile bit data Tick100ms; // 100ms volatile bit data Tick1s; // 1s //function prototypes static bit setUartBaudRate(UartBaudRates baudRate); static bit putUartChar(U8 outChar); static bit getUartChar(U8 *pInChar); void TMR_Init() { TR0 = 0; // stop Timer 0 ET0 = 0; // disable Timer 0 int TMOD &= T0_MODE_MASK; // configure Timer 0 TMOD |= T0_16BIT_TIMER; // 16-bit timer mode TL0 = TIMER0_10MS_LO; // set reload values TH0 = TIMER0_10MS_HI; Tick10ms = 0; // reset time regions Tick100ms = 0; Tick1s = 0; ET0 = 1; // enable Timer 0 int TR0 = 1; // start Timer 0 } bit initUart(UartBaudRates baudRate) { ES = 0; // stop serial ints if (setUartBaudRate(baudRate)) return 1; // Set the baud rate SCON = SCON_8N1 | SCON_REN; // Setup the serial port s_rxRingEmpty = 1; // flag rings as empty s_txRingEmpty = 1; s_rxWrIdx = 0; // Setup ring buffer pointers s_rxRdIdx = 0; s_txWrIdx = 0; s_txRdIdx = 0; s_translateEol = 1; // EOL translate ES = 1; // start serial ints return 0; } static bit setUartBaudRate(UartBaudRates baudRate) { static const S8 code baudRateTable2x[NUM_BAUD_RATES] = { // 1200 2400 9600 19200 38400 57600 115200 #if XTAL_FREQ == XTAL_7_3728MHZ -192, -96, -24, -12, -6, -4, -2 // timer reload values #elif XTAL_FREQ == XTAL_11_059MHZ -48, -24, -6, -3, 0, -1, 0 #else // Add more if needed. # error Pick a known XTAL frequency from list provided in this file. #endif }; static const S8 code baudRateTable1x[NUM_BAUD_RATES] = { // 1200 2400 9600 19200 38400 57600 115200 #if XTAL_FREQ == XTAL_7_3728MHZ -384, -192, -48, -24, -12, -8, -4 #elif XTAL_FREQ == XTAL_11_059MHZ -24, -12, -3, 0, 0, 0, 0 #else # error Pick a known XTAL frequency from list provided in this file. #endif }; S8 data th1Value; bit data ieEs; // Look for cases where we don't want to or can't change the baud rate. if (BAUD_RATE_NO_CHANGE == baudRate || s_currentBaudRate == baudRate) { return 0; } // outside of list - error if ((unsigned int) baudRate > NUM_BAUD_RATES) { return 1; } PCON |= PCON_SMOD; // See if we *can* set the desired baud rate th1Value = baudRateTable2x[baudRate]; // reload values if (!th1Value) { // if zero (not available) r_pcon &= ~PCON_SMOD; // turn off baud rate doubler th1Value = baudRateTable1x[baudRate]; // pull values if (!th1Value) return 1; // if zero again, error } ieEs = _testbit_(ES); // Preserve and clear serial interrupt enable ET1 = 0; // no Timer 1 interrupt s_currentBaudRate = baudRate; // Save this for getUartOption() TR1 = 0; // stop timer 1 TMOD &= T1_MODE_MASK; // Config Timer 1 for baud rate generation TMOD |= T1_8BIT_AUTO_RELOAD; TH1 = (U8) th1Value; // load timer TL1 = (U8) th1Value; TR1 = 1; // start timer 1 ES = ieEs; // restore previous setting return 0; } // repost with more comments static void uartIsr(void) interrupt 4 using 1 { static U8 data inChar; if (RI) { // char waiting RI = 0; // clear interrupt inChar = SBUF; // grab char, but don't put it in buffer yet if (s_rxRingEmpty || s_rxWrIdx != s_rxRdIdx) { // if room in buffer or pointers unequal s_rxRing[s_rxWrIdx] = inChar; // put into ring buffer ++s_rxWrIdx; // update index pointer #if RX_RING_SIZE != 256 // ask Mark Odell about this part s_rxWrIdx %= RX_RING_SIZE; #endif s_rxRingEmpty = 0; // not empty? } } if (TI) { // char to send TI = 0; // clear interrupt if (s_txRdIdx != s_txWrIdx) { // if index pointers not equal SBUF = s_txRing[s_txRdIdx]; // send char ++s_txRdIdx; // update index pointer #if TX_RING_SIZE != 256 // ask Mark Odell about this part s_txRdIdx %= TX_RING_SIZE; #endif } else { s_txRingEmpty = 1; // declare empty after last TI event } } }
I was initially looking for any guidelines or rules-of-thumb when running multiple ISRs.
In that case, you were looking for the completely wrong type of advice. Your problem has nothing to do with interrupts or ISRs, and it is completely invisible in the code you posted first.
Instead, you should consider if this line is really doing what you want them to do, because it will completely mess up any configuration of Timer 0.
TMOD &= T1_MODE_MASK; // Config Timer 1 for baud rate generation
I was initially looking for any guidelines or rules-of-thumb when running multiple ISRs well the big one is KISS Keep ISRs Short and Simple.
The one ISR you show is fairly so (a note: if you keep ring buffers on a power of two size, you do not need the slooow divide, an and will do)
s_txRdIdx seems to indicate that you are using a short where a char will do, that will increase the ISR processing time about tenfold.
Is it possible that you have interrupts at differenr priority (as set in the IP SFR) using the same register bank. ?
Erik
Wow, that was it - the second TMOD config was blowing away the first. You guys are good. :)
Changes in TMR_Init:
TMOD &= 0xF0; // clear Timer 0, mask off Timer 1 TMOD |= 0x01; // Timer 0 Mode 1 (16-bit timer )
Changes in setUartBaudRate:
TMOD &= 0x0F; // clear Timer 1, mask off Timer 0 TMOD |= 0x20; // Timer 1 Mode 2 (8-bit auto-reload)
I will also make the changes to the ISRs. Thanks guys.