Rainbow Electronics DS1680 - Manual (Page 15)

DS1680
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PARALLEL INTERFACE
The ADC output is available on the data bus at pins D0–D7. A logic 0 on COEN will enable data onto the
data bus so that the DS1680 can be used in parallel with other devices. PEN_SELECT and
OUT_SELECT are used to decode which analog output (X-, Y-, AIN0, or AIN1) is output on the data bus
when COEN is asserted low. Since the device offers 10-bit resolution, the BHE pin is used to decode the
10 bits of data on the data bus. A logic 1 on BHE will enable data bits B2–B9. A logic 0 will enable data
bits B0–B1 along with the six LSBs = 0. The status pin ( NEW_DATA ) pulses low to indicate that new
coordinate or conversion is available. The output can be read while NEW_DATA is low or after it has
gone high. Output selection and parallel data format is shown below.
OUTPUT SELECTION Table 4
PEN_SELECT OUT_SELECT ANALOG OUTPUT
0 0 AIN0
0 1 AIN1
1 0 X-
1 1 Y-
PARALLEL DATA FORMAT
MSB LSB
High Byte BHE = 1 B9 B8 B7 B6 B5 B4 B3 B2
Low Byte BHE = 0 B1 B0 0 0 0 0 0 0
POWER MANAGEMENT (ADC AND PEN-INPUT PROCESSOR)
The DS1680 analog circuitry can be placed into a low-power mode by asserting and holding the
PD_RESET pin at logic 1. Normal operation will resume when PD_RESET is returned to logic 0.
To further conserve power, the pen-detection circuitry will automatically switch the analog circuitry to
power-down mode whenever there is no pen input detected for more than three seconds. Normal
operation will automatically resume when any one of the following three events occur: pen down is
detected, the CONVERT signal is activated, or chip is reset (PD_RESET pulled to logic 1 and then
returned to logic 0).