Add support for Teensy-LC DAC

teensy3/analog.c

 	if (val < 0) val = 0;  // TODO: saturate instruction?
 	else if (val > 4095) val = 4095;
 	*(int16_t *)&(DAC0_DAT0L) = val;
+#elif defined(__MKL26Z64__)
+	SIM_SCGC6 |= SIM_SCGC6_DAC0;
+	if (analog_reference_internal == 0) {
+		// use 3.3V VDDA power as the reference (this is the default)
+		DAC0_C0 = DAC_C0_DACEN | DAC_C0_DACRFS | DAC_C0_DACSWTRG; // 3.3V VDDA
+	} else {
+		// use whatever voltage is on the AREF pin
+		DAC0_C0 = DAC_C0_DACEN | DAC_C0_DACSWTRG; // 3.3V VDDA
+	}
+	if (val < 0) val = 0;
+	else if (val > 4095) val = 4095;
+	*(int16_t *)&(DAC0_DAT0L) = val;
 #endif
 }
 

teensy3/kinetis.h

 #define SIM_SCGC5_TSI			((uint32_t)0x00000020)		// Touch Sense Input TSI Clock Gate Control
 #define SIM_SCGC5_LPTIMER		((uint32_t)0x00000001)		// Low Power Timer Access Control
 #define SIM_SCGC6		(*(volatile uint32_t *)0x4004803C) // System Clock Gating Control Register 6
+#define SIM_SCGC6_DAC0			((uint32_t)0x80000000)		// DAC on Kinetis-L
 #define SIM_SCGC6_RTC			((uint32_t)0x20000000)		// RTC Access
 #define SIM_SCGC6_ADC0			((uint32_t)0x08000000)		// ADC0 Clock Gate Control
 #define SIM_SCGC6_FTM1			((uint32_t)0x02000000)		// FTM1 Clock Gate Control

teensy3/pins_teensy.c

 		analogWriteDAC0(val);
 		return;
 	}
+#elif defined(__MKL26Z64__)
+	if (pin == A12) {
+		uint8_t res = analog_write_res;
+		if (res < 12) {
+			val <<= 12 - res;
+		} else if (res > 12) {
+			val >>= res - 12;
+		}
+		analogWriteDAC0(val);
+		return;
+	}
 #endif
 
 	max = 1 << analog_write_res;