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Last modified on 4 January 2010, at 21:50

MEA8000 I/O Ports and Pinouts

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Philips/Mullard/Signetics MEA8000 Speech Chip

Status Register (R)

 7     REQ   Data Request (0=Busy, 1=Data Request)
 6-0   N/A   Not used

Data Register (W) (A0=0)

If the device is in STOP mode, then first data byte must be the 8bit pitch: 

 7-0   PITCH Starting Pitch           (8bit) (sawtooth) (don't care for noise)

thereafter, 32bit Speech Frame(s) can be written: 

 31-30 BW1   2bit Bandwidth is? 1st formant
 29-28 BW2   2bit Bandwidth of 2nd formant      bandwidth "4 KH"
 27-26 BW3   2bit Bandwidth of 3rd formant
 25-24 BW4   2bit Bandwidth of 4th formant
 N/A   FM4   0bit Frequency of 4th formant (fixed at 3500 Hz)
 23-21 FM3   3bit Frequency of 3rd formant
 20-16 FM2   5bit Frequency of 2nd formant      resonance frequency
 15-11 FM1   5bit Frequency of 1st formant
 10-7  AMPL  4bit Amplitude (volume)
 6-5   FD    2bit Frame Duration (8,16,32,64 ms)
 4-0   PI    5bit Pitch Increment (signed?) (?=Noise)

the 32bit parameter is split into 4bytes (starting with bit31-24). wait for REQ=1 before sending further speech frame(s).

Command Register (W) (A0=1)

 7-5   N/A  Not used
 4     STOP Stop        (0=No change, 1=Force Instant Stop)
 3-2   CONT Continue    (0=No change, 1=No change, 2=Slow Stop, 3=Continue)
 1-0   ROE  /REQ Output (0=No change, 1=No change, 2=Disable, 3=Enable)
  • STOP Mode: Output is silent, REQ is set, next write to Data register will be treated as 8bit Starting Pitch value, to be followed by the 32bit Speech Frame data, thereafter sound output will start (and the device is no longer in STOP Mode).

After completing a speech frame (which takes 8..64 ms), the CPU can output another speech frame (by writing another 32bit to the data register), if the CPU doesn't supply new data then Slow Stop or Continue will occur (as selected in the Command Register).

  • SLOW STOP Mode: After completing the last speech frame, the last frame will be repeated once (with decaying amplitude & same pitch), thereafter, STOP mode is entered.
  • CONTINUE Mode: The last speech frame will be repeated indefinetly (until a new 32bit data has been supplyied, or until SLOW STOP mode is selected, or until INSTANT STOP os forced).

MEA8000 Pinouts

 1-GND   4-D6   7-D3   10-D0    13-VCC     16-OSC IN   19-REF      22-/RD
 2-/REQ  5-D5   8-D2   11-A0    14-/REQEN  17-OSC OUT  20-OUT      23-/WR
 3-D7    6-D4   9-D1   12-/CE   15-NC      18-CLK IN   21-CLK OUT  24-TEST