TV Converter Box User Manual

Conversation Between the TLV1562 and the DSP
14 SLAA040
7.3 Mono Interrupt Driven Mode Using CSTART
Use the CSTART signal when two or more ADCs must sample/convert signals
at the same time. Instead of the RD
signal, the timing for sampling and converting
is started with the edges of the CSTART
signal. The RD signal is still required to
get the data out of the ADC and onto the bus.
Table 8. DSP Algorithm for Mono Interrupt Driven Mode Using CSTART
Wait cycles for the DSP internally (40MHz DSPCLK):
STEPS TIMING, NOTES
APD=0
ADCSYCLK
= 7.5 MHz
APD=0
ADCSYCLK
= 10 MHz
APD=1
ADCSYCLK
= 10 MHz
APD=1
ADCSYCLK
= 10 MHz
1. Set CS Deselect ADC
2. Clear CSTART tTis starts sampling
3. Wait for t
W(CSTARTL)
t
W(CSTARTL)
= 100 ns (APD=0)
t
W(CSTARTL)
= 600 ns (APD=1)
≥4 ≥4 ≥24 ≥24
4. Set CSTART This starts the conversion
5. Wait until INT goes low Alternative: ignore the INT signal,
wait 14ns+5 ADCSYSCLK and goto
step number 7
≥33 ≥21 ≥33 ≥21
6. Wait the time t
D(INTL-CSI)
t
D(INTL-CSI)
= 10 ns ≥1 ≥1 ≥1 ≥1
7. Clear CS Select the ADC
8. Clear RD Start communication
9. Wait the time t
EN(DATAOUT)
t
EN(DATAOUT)
= 41 ns ≥2 ≥2 ≥2 ≥2
10. Read sample out from the data port;
Reset RD
signal
11. Set CS Deselect ADC
12. Go to step 2 for the next samples