Datasheet

AD9558 Data Sheet
Rev. B | Page 48 of 104
Programming the EEPROM to Configure an M Pin to
Control Synchronization of Clock Distribution
A special EEPROM loading sequence is required to use the
EEPROM to load the registers and to use an M pin to
enable/disable outputs.
To control the output sync function by using an M pin, perform
the following steps:
1. Enable the M pins by writing Register 0x0200 = 0x01.
2. Issue an I/O update (Register 0x0005 = 0x01).
3. Set the appropriate M pin function (see the Clock
Distribution Synchronization section for details).
If this sequence is not performed, a SYNC pulse is issued
automatically.
The following changes write Register 0x0200 first and then issue
an I/O update before writing the remaining M pin configuration
registers in Register 0x0201 to Register 0x0208.
The default EEPROM loading sequence from Register 0x0E10 to
Register 0x0E16 is unchanged. The following steps must be
inserted into the EEPROM storage sequence:
1. R0x0E17 = 0x00 # Write one byte
2. R0x0E18 = 0x02 # at Register 0x0200
3. R0x0E19 = 0x00 #
4. R0x0E1A = 0x80 # Op code for I/O
Update R0x0E1B = 0x10 # Transfer 17 instead of 18 bytes
5. R0x0E1C = 0x02 # Transfer starts at Register address
6. R0x0E1D = 0x01 # 0x0201 instead of 0x0200
The rest of the EEPROM loading sequence is the same as the
default EEPROM loading sequence, except that the register
address of the EEPROM storage sequence is shifted down four
bytes from the default. For example,
• R0x0E1E = default value of Register 0x0E1A = 0x2E
• R0x0E1F = default value of Register 0x0E1B = 0x03
• R0x0E20 = default value of Register 0x0E1C = 0x00
• …
• R0x0E40 = default value of Register 0x0E1C = 0x3C = 0xFF
(end of data)