7730 speech encoder/decoder (SED) encodes PCM data to ADPCM data 19881017/wjvg 0 data 1 status r .......1 8/16 bit serial input data length r ......1. 8/16 bit serial output data length r .....1.. first/second byte transferred (klopt niet) r ....0... not used r ...1.... data register is 16/8 bit (16 bit for 2nd byte of threshold) r ..1..... speech detected/silence interval r .0...... not used r 1....... data request After reset and initializing for input: 84 80 90 87 After a reset, and after 'data request' has come up (status, not pin), a command byte must be put in the data register: w ...00000 not used w ..1..... 8/16 bit (8 bit is u-law) w .1...... 4/3 bit ADPCM data w 1....... encode/decode If put in encode mode, two more bytes must be put in the data register (after two more data request's): w llllllll threshold low value w 0hhhhhhh threshold high value, sign is 0 end