What voltage should be supplied to the Vref pin for proper operation?
The Vref pin is for ADC reference voltage, so 20K to 30K is acceptable. • What is the recommended input audio voltage level for optimum performance? The HM2006/2007 AGC (automatic gain control) specification is 0 dB to 40dB. For example, an acceptable input level range is 20mV to 0.2V. • Can any one of the crystal connection pins (X1, X2) be used as clock inputs or outputs? X1 can be used for input and X2 can be used for output. • What is the required SRAM speed? The SRAM access time should be less than 200ns. • Are K1-K4 in a high impedance state in all cases expect for a read cycle? In the write cycle, K1-K4 are inputs and in all other cases they are outputs. [Corin’s note: this is very important! The HM2007 is usually driving the K-bus, so take care to not drive it from the microcontroller, too. I bridged the two chips with 10K resistors for an added measure of safety.] • What is the response time after the read/write command? The response time is about 5us. • Would loading “null da
