[I2C] Writing to register has no effect about sc16is740rk HOT 3 OPEN

   bool SC16IS740Base::begin(int baudRate, uint8_t options) {
preBegin();

// My test board uses this oscillator
// KC3225K1.84320C1GE00
// OSC XO 1.8432MHz CMOS SMD $1.36
// https://www.digikey.com/product-detail/en/avx-corp-kyocera-corp/KC3225K1.84320C1GE00/1253-1488-1-ND/5322590
// Another suggested frequency from the data sheet is 3.072 MHz

// The divider devices the clock frequency to 16x the baud rate
int div = oscillatorHz / (baudRate * 16);

// Read Status
readRegister(LCR_REG); // returns 0 on startup

// Set Enhanced Function Bit first
writeRegister(LCR_REG, EFR_REGISTER_START); // Set to LCR 0xbf to enable access to EFR register
writeRegister(EFR_REG, EFR_ENHANCED_BIT); // Set 4th bit to 1 (0x10) to enable enhanced functions.
writeRegister(LCR_REG, LCR_SPECIAL_END); // Set LCR to 0x00 as originally read.
writeRegister(IEF_REG, EFR_ENHANCED_BIT); // Set 4th bit to 1 (0x10) to enable sleep mode

writeRegister(LCR_REG, LCR_SPECIAL_START); // 0x80 
writeRegister(DLL_REG, div & 0xff);
writeRegister(DLH_REG, div >> 8);
writeRegister(LCR_REG, LCR_SPECIAL_END); // 0x00


writeRegister(LCR_REG, options & 0x3f);

// Enable FIFOs
writeRegister(FCR_IIR_REG, 0x07); // Enable FIFO, Clear RX and TX FIFOs

// Also MCR?
return true;
   }

0000010331 [dryp.extser] TRACE: readRegister reg=3 value=0 // LCR is 0 from the get-go
0000010331 [dryp.extser] TRACE: writeRegister reg=3 value=191 stat=0 // Write 0xbf to LCR
0000010332 [dryp.extser] TRACE: writeRegister reg=2 value=16 stat=3  // Write 0x10 to EFR, timeout on address? 
0000010333 [dryp.extser] TRACE: writeRegister reg=3 value=0 stat=0  // Write 0 to LCR as originally read
0000010333 [dryp.extser] TRACE: writeRegister reg=1 value=16 stat=0  // Write 0x10 to IEF/IER REG (sleep mode bit), works? But should only work if EFR bit has been set, which seems like it fails?

0000010334 [dryp.extser] TRACE: writeRegister reg=3 value=128 stat=0 // Write 0x80 to LCR
0000010335 [dryp.extser] TRACE: writeRegister reg=0 value=12 stat=0  // Write to DLL reg
0000010335 [dryp.extser] TRACE: writeRegister reg=1 value=0 stat=0  // Write to DLH reg
0000010336 [dryp.extser] TRACE: writeRegister reg=3 value=0 stat=0   // Write 0x00 to LCR reg as originally read
0000010336 [dryp.extser] TRACE: writeRegister reg=3 value=3 stat=0 // Write options to LCR reg
0000010337 [dryp.extser] TRACE: writeRegister reg=2 value=7 stat=3 // Write 0x07 to FCR_IIR_REG, but fails?