Debug TPM settings

- Disable prescaler
- Check FLL/PLL select in SOPT2
- Optimize CLOCK/NSEC conversion
- Set oscillator to high gain operation
- Add debug code for TPM/PIT counters

diff --git a/hw2/main.cpp b/hw2/main.cpp
index 52e84aa7b242cfbe45a3a7b1c1ce7042ab28f4ed..47b701b4f2d2c269711032a59e082f3222b4783b 100644 (file)
--- a/hw2/main.cpp
+++ b/hw2/main.cpp
@@ -111,8 +111,11 @@ void time_printf(const char *label, uint64_t local)
  * Signal generation *
  *********************/
 
-#define EMIT_CLOCKS(nsec) ((uint16_t)((nsec) * 24 / 1000))
-#define EMIT_NSEC(clocks) ((uint16_t)((clocks) * 1000 / 24))
+// for 24 Mhz clock, 24/1000 = 3/125
+// for 48 Mhz clock  48/1000 = 6/125
+// for 50 Mhz clock  50/1000 = 1/20  (FLL/2)
+#define EMIT_CLOCKS(nsec) ((uint16_t)((nsec)   / 20))
+#define EMIT_NSEC(clocks) ((uint16_t)((clocks) * 20))
 
 static uint32_t *emit_pcr    = 0; // transmit pin name
 
@@ -132,6 +135,16 @@ void emit_init(int alt, PinName pin, PinMode mode)
        SIM->SCGC6            |= SIM_SCGC6_TPM1_MASK;
        SIM->SOPT2            |= SIM_SOPT2_TPMSRC(1);
 
+       // Debug print on SOPT2
+       // -- mbed may set PLLFLL when configuring UART0
+       sirq_printf("SOPT2: u0src=%d tpmsrc=%d %s %s clkos=%d %s\r\n",
+               (SIM->SOPT2 & SIM_SOPT2_UART0SRC_MASK)     >> SIM_SOPT2_UART0SRC_SHIFT,
+               (SIM->SOPT2 & SIM_SOPT2_TPMSRC_MASK)       >> SIM_SOPT2_TPMSRC_SHIFT,
+               (SIM->SOPT2 & SIM_SOPT2_UART0SRC_MASK)     ? "USBSRC" : "usbsrc",
+               (SIM->SOPT2 & SIM_SOPT2_PLLFLLSEL_MASK)    ? "PLL/2"  : "FLL",
+               (SIM->SOPT2 & SIM_SOPT2_CLKOUTSEL_MASK)    >> SIM_SOPT2_CLKOUTSEL_SHIFT,
+               (SIM->SOPT2 & SIM_SOPT2_RTCCLKOUTSEL_MASK) ? "RTCOS"  : "rtcos");
+
        // Set pin mode
        emit_pcr[0]            = PORT_PCR_ISF_MASK
                               | PORT_PCR_MUX(alt)
@@ -184,9 +197,22 @@ void emit_schedule(uint64_t when)
 
        // Start the timer
        TPM1->SC               = TPM_SC_TOF_MASK
-                              | TPM_SC_PS(1)
+                              | TPM_SC_PS(0)
                               | TPM_SC_CMOD(1);
 
+       // Clock testing
+       uint32_t test_tpm0 = TPM1->SC;
+       uint32_t test_pit0 = PIT->CHANNEL[1].CVAL;
+       for (int i = 0; i < 1000; i++)
+               asm("nop");
+       uint32_t test_tpm1 = TPM1->SC;
+       uint32_t test_pit1 = PIT->CHANNEL[1].CVAL;
+       uint32_t test_tpm  = test_tpm0 - test_tpm0;
+       uint32_t test_pit  = test_pit1 - test_pit0;
+       sirq_printf("pit/tpm: tpm=%04hx/%04hx=%d pit=%08x/%08x=%d\r\n",
+                       test_tpm0, test_tpm1, test_tpm,
+                       test_pit0, test_pit1, test_pit);
+
        // Debug output
        //sirq_printf("emitting event\r\n");
 }
@@ -649,6 +675,9 @@ int main(int argc, char **argv)
        serial_tdma_rcv = tdma_rcv;
        serial_tdma_xmt = tdma_xmt;
 
+       // configure crystal oscilator for high gain operation
+       MCG->C2 |= MCG_C2_HGO0_MASK;
+
        // Test clocks
        //MCG->C1    = 0x05; // was 0x1A
        //MCG->C2    = 0x2C; // was 0x24