Added si5351 driver

examples/si5351/main.go

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+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/si5351"
+)
+
+// Simple demo of the SI5351 clock generator.
+// This is like the Arduino library example:
+//   https://github.com/adafruit/Adafruit_Si5351_Library/blob/master/examples/si5351/si5351.ino
+// Which will configure the chip with:
+//  - PLL A at 900mhz
+//  - PLL B at 616.66667mhz
+//  - Clock 0 at 112.5mhz, using PLL A as a source divided by 8
+//  - Clock 1 at 13.5531mhz, using PLL B as a source divided by 45.5
+//  - Clock 2 at 10.76khz, using PLL B as a source divided by 900 and further divided with an R divider of 64.
+
+func main() {
+
+	time.Sleep(5 * time.Second)
+
+	println("Si5351 Clockgen Test")
+	println()
+
+	// Configure I2C bus
+	machine.I2C0.Configure(machine.I2CConfig{})
+
+	// Create driver instance
+	clockgen := si5351.New(machine.I2C0)
+
+	// Verify device wired properly
+	if !clockgen.Connected() {
+		for {
+			println("Ooops, no Si5351 detected ... Check your wiring!")
+			time.Sleep(time.Second)
+		}
+	}
+
+	// Initialise device
+	clockgen.Configure()
+
+	// Now configue the PLLs and clock outputs.
+	// The PLLs can be configured with a multiplier and division of the on-board
+	// 25mhz reference crystal.  For example configure PLL A to 900mhz by multiplying
+	// by 36.  This uses an integer multiplier which is more accurate over time
+	// but allows less of a range of frequencies compared to a fractional
+	// multiplier shown next.
+	clockgen.ConfigurePLL(si5351.PLL_A, 36, 0, 1) // Multiply 25mhz by 36
+	println("PLL A frequency: 900mhz")
+
+	// And next configure PLL B to 616.6667mhz by multiplying 25mhz by 24.667 using
+	// the fractional multiplier configuration.  Notice you specify the integer
+	// multiplier and then a numerator and denominator as separate values, i.e.
+	// numerator 2 and denominator 3 means 2/3 or 0.667.  This fractional
+	// configuration is susceptible to some jitter over time but can set a larger
+	// range of frequencies.
+	clockgen.ConfigurePLL(si5351.PLL_B, 24, 2, 3) // Multiply 25mhz by 24.667 (24 2/3)
+	println("PLL B frequency: 616.6667mhz")
+
+	// Now configure the clock outputs.  Each is driven by a PLL frequency as input
+	// and then further divides that down to a specific frequency.
+	// Configure clock 0 output to be driven by PLL A divided by 8, so an output
+	// of 112.5mhz (900mhz / 8).  Again this uses the most precise integer division
+	// but can't set as wide a range of values.
+	clockgen.ConfigureMultisynth(0, si5351.PLL_A, 8, 0, 1) // Divide by 8 (8 0/1)
+	println("Clock 0: 112.5mhz")
+
+	// Next configure clock 1 to be driven by PLL B divided by 45.5 to get
+	// 13.5531mhz (616.6667mhz / 45.5).  This uses fractional division and again
+	// notice the numerator and denominator are explicitly specified.  This is less
+	// precise but allows a large range of frequencies.
+	clockgen.ConfigureMultisynth(1, si5351.PLL_B, 45, 1, 2) // Divide by 45.5 (45 1/2)
+	println("Clock 1: 13.5531mhz")
+
+	// Finally configure clock 2 to be driven by PLL B divided once by 900 to get
+	// down to 685.15 khz and then further divided by a special R divider that
+	// divides 685.15 khz by 64 to get a final output of 10.706khz.
+	clockgen.ConfigureMultisynth(2, si5351.PLL_B, 900, 0, 1) // Divide by 900 (900 0/1)
+	// Set the R divider, this can be a value of:
+	//  - R_DIV_1: divider of 1
+	//  - R_DIV_2: divider of 2
+	//  - R_DIV_4: divider of 4
+	//  - R_DIV_8: divider of 8
+	//  - R_DIV_16: divider of 16
+	//  - R_DIV_32: divider of 32
+	//  - R_DIV_64: divider of 64
+	//  - R_DIV_128: divider of 128
+	clockgen.ConfigureRdiv(2, si5351.R_DIV_64)
+	println("Clock 2: 10.706khz")
+
+	// After configuring PLLs and clocks, enable the outputs.
+	clockgen.EnableOutputs()
+
+	for {
+		time.Sleep(5 * time.Second)
+		println()
+		println("Clock 0: 112.5mhz")
+		println("Clock 1: 13.5531mhz")
+		println("Clock 2: 10.706khz")
+	}
+
+}

si5351/registers.go

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+package si5351
+
+// The I2C address which this device listens to.
+const AddressDefault = 0x60     // Assumes ADDR pin is low
+const AddressAlternative = 0x61 // Assumes ADDR pin is high
+
+const (
+	OUTPUT_ENABLE_CONTROL = 3
+
+	CLK0_CONTROL = 16
+	CLK1_CONTROL = 17
+	CLK2_CONTROL = 18
+	CLK3_CONTROL = 19
+	CLK4_CONTROL = 20
+	CLK5_CONTROL = 21
+	CLK6_CONTROL = 22
+	CLK7_CONTROL = 23
+
+	MULTISYNTH0_PARAMETERS_1 = 42
+	MULTISYNTH0_PARAMETERS_3 = 44
+	MULTISYNTH1_PARAMETERS_1 = 50
+	MULTISYNTH1_PARAMETERS_3 = 52
+	MULTISYNTH2_PARAMETERS_1 = 58
+	MULTISYNTH2_PARAMETERS_3 = 60
+
+	SPREAD_SPECTRUM_PARAMETERS = 149
+
+	PLL_RESET = 177
+
+	CRYSTAL_INTERNAL_LOAD_CAPACITANCE = 183
+)
+
+const (
+	CRYSTAL_LOAD_6PF  = (1 << 6)
+	CRYSTAL_LOAD_8PF  = (2 << 6)
+	CRYSTAL_LOAD_10PF = (3 << 6)
+)
+
+const (
+	CRYSTAL_FREQ_25MHZ = 25000000
+	CRYSTAL_FREQ_27MHZ = 27000000
+)
+
+const (
+	PLL_A = iota
+	PLL_B
+)
+
+const (
+	R_DIV_1   = 0
+	R_DIV_2   = 1
+	R_DIV_4   = 2
+	R_DIV_8   = 3
+	R_DIV_16  = 4
+	R_DIV_32  = 5
+	R_DIV_64  = 6
+	R_DIV_128 = 7
+)
+
+const (
+	MULTISYNTH_DIV_4 = 4
+	MULTISYNTH_DIV_6 = 6
+	MULTISYNTH_DIV_8 = 8
+)