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altso3 [2026/06/16 02:38] – created adminaltso3 [2026/07/18 04:17] (current) – admin
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 ====== AltSO3 ====== ====== AltSO3 ======
  
 +Exploring modern alternatives to the Kenwood SO-3 TCXO. Watch this space, maybe?
  
-==== AltSO3 ==== +{{:altso3:altso3_v001.jpeg?600 |}}
-Micropython code for programming the MS5351M. Not yet tested. +
- +
-<file python main.py> +
-import machine +
-import time +
- +
-I2C_ADDR = 0x60 # Default Si5351A I2C address +
-I2C_SDA_PIN = 8   # RP2040 GP8 +
-I2C_SCL_PIN = 9   # RP2040 GP9 +
- +
-def setup_si5351(i2c): +
-    def write_reg(reg, val): +
-        i2c.writeto_mem(I2C_ADDR, reg, bytes([val])) +
- +
-    # 1. Disable all outputs +
-    write_reg(3, 0xFF) +
- +
-    # 2. Power down all output drivers +
-    for reg in range(16, 24): +
-        write_reg(reg, 0x80) +
- +
-    # 3. Calculate and configure PLLA registers for 624 MHz +
-    # Multiplier: a=24, b=24, c=25 +
-    a_pll, b_pll, c_pll = 24, 24, 25 +
-    p1_pll = 128 * a_pll + int(128 * b_pll / c_pll) - 512 +
-    p2_pll = 128 * b_pll - c_pll * int(128 * b_pll / c_pll) +
-    p3_pll = c_pll +
- +
-    write_reg(26, (p3_pll >> 8) & 0xFF) +
-    write_reg(27, p3_pll & 0xFF) +
-    write_reg(28, ((p1_pll >> 16) & 0x03) | (((p2_pll >> 16) & 0x03) << 4)) +
-    write_reg(29, (p1_pll >> 8) & 0xFF) +
-    write_reg(30, p1_pll & 0xFF) +
-    write_reg(31, (((p3_pll >> 16) & 0x0F) << 4) | ((p2_pll >> 16) & 0x0F)) +
-    write_reg(32, (p2_pll >> 8) & 0xFF) +
-    write_reg(33, p2_pll & 0xFF) +
- +
-    # 4. Calculate and configure MultiSynth 0 registers for divide-by-40 +
-    # Divider: a=40, b=0, c=1 +
-    a_ms, b_ms, c_ms = 40, 0, 1 +
-    p1_ms = 128 * a_ms + int(128 * b_ms / c_ms) - 512 +
-    p2_ms = 128 * b_ms - c_ms * int(128 * b_ms / c_ms) +
-    p3_ms = c_ms +
- +
-    write_reg(42, (p3_ms >> 8) & 0xFF) +
-    write_reg(43, p3_ms & 0xFF) +
-    write_reg(44, ((p1_ms >> 16) & 0x03) | (((p2_ms >> 16) & 0x03) << 4)) +
-    write_reg(45, (p1_ms >> 8) & 0xFF) +
-    write_reg(46, p1_ms & 0xFF) +
-    write_reg(47, (((p3_ms >> 16) & 0x0F) << 4) | ((p2_ms >> 16) & 0x0F)) +
-    write_reg(48, (p2_ms >> 8) & 0xFF) +
-    write_reg(49, p2_ms & 0xFF) +
- +
-    # 5. Connect MS0 to CLK0, Power Up, Integer Mode, PLLA Source, 8mA drive +
-    # 0x4F = 0b01001111 +
-    write_reg(16, 0x4F) +
- +
-    # 6. Reset PLLA +
-    write_reg(177, 0x20) +
- +
-    # 7. Enable CLK0 +
-    write_reg(3, 0xFE) +
- +
-    print("Success: Si5351A configured to output 15.6 MHz on CLK0 in RAM.") +
- +
-def burn_to_nvram(i2c): +
-    """ +
-    WARNING: The Si5351A NVRAM is One-Time Programmable (OTP). +
-    This permanently burns the current RAM configuration into the chip. +
-    """ +
-    print("⚠️ WARNING: Initiating NVRAM burn sequence...") +
-    print("This is a One-Time Programmable (OTP) operation!") +
-    time.sleep(3) # Give user a chance to interrupt execution (Ctrl+C) if accidental +
-     +
-    def write_reg(reg, val): +
-        i2c.writeto_mem(I2C_ADDR, reg, bytes([val])) +
-         +
-    # Write 0xC0 to register 161 (NVM_WRITE) to trigger NVRAM burn +
-    write_reg(161, 0xC0) +
-    time.sleep(1) # Wait for NVM burn to complete +
-    print("✅ NVRAM burn sequence completed. This configuration is now permanent.") +
- +
-if __name__ == "__main__": +
-    # Initialize I2C bus 0 +
-    i2c = machine.I2C(0, scl=machine.Pin(I2C_SCL_PIN), sda=machine.Pin(I2C_SDA_PIN), freq=400000) +
-     +
-    # 1. Configure the RAM first to test the output +
-    setup_si5351(i2c) +
-     +
-    # 2. ⚠️ DANGER ZONE: Uncomment the line below ONLY AFTER verifying the 15.6 MHz  +
-    # output with an oscilloscope or frequency counter. +
-    # burn_to_nvram(i2c) +
-</file>+
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