Datasheet

Data Sheet ADAS1000-3/ADAS1000-4
Rev. A | Page 71 of 76
Example 6: Writing to Master and Slave Devices and Streaming Conversion Data
This example uses the ADAS1000-3 as the slave device and the
ADAS1000 as the master device to achieve a configuration with
eight input electrodes and one right leg drive.
Slave Configuration (ADAS1000-3)
1. Write 1 configures the FRMCTL register to output five
words per frame/packet. The frame/packet of words
consists of the header, three ECG words, and lead-off. The
frame is configured to always send, irrespective of ready
status. The slave ADAS1000-3 is in electrode mode format
with a data rate of 2 kHz.
2. Write 2 configures the CMREFCTL register to receive an
external common mode from the master.
3. Write 3 addresses the ECGCTL register, enabling all
channels into a gain of 1.4, low noise mode. It configures
the device as a slave, in gang mode and driven from the
CLK_IN input source (derived from master ADAS1000).
The ADAS1000-3 slave is also put into conversion mode
in this write, but waits for the SYNC_GANG signal from
the master device before it starts converting.
Master Configuration (ADAS1000)
1. Write 4 configures the FRMCTL register to output seven
words per frame/packet (note that this differs from the
number of words in a frame available from the slave
device). The frame/packet of words consists of the header,
five ECG words, pace, respiration magnitude, and lead-off.
In this example, the frame is configured to always send
irrespective of ready status. The master, ADAS1000, is in
vector mode format with a data rate of 2 kHz. Similar
to the slave device, the master could be configured for
electrode mode; the host controller would then be required
to make the lead calculations.
2. Write 5 configures the CMREFCTL register for CM =
WCT = (LA + LL + RA)/3; RLD is enabled onto
RLD_OUT electrode. The shield amplifier is enabled.
The CM = WCT signal is driven out of the master device
(CM_OUT) into the slave device (CM_IN).
3. Write 6 addresses the ECGCTL register, enabling all
channels into a gain of 1.4, low noise mode. It configures
the device as a master in gang mode and driven from
the XTAL input source. The ADAS1000 master is set to
differential input, which places it in analog lead mode.
This ECGCTL register write puts the master into
conversion mode, where the device sends an edge on
the SYNC_GANG pin to the slave device to trigger the
simultaneous conversions of both devices.
4. Write 7 issues the read command to both devices to start
putting the converted and decimated data out on the
respective SDO pins.
5. Continue to issue SCLK cycles to read the converted data
at the configured packet data rate.
Table 59. Example 6: Writing to Master and Slave Devices and Streaming Conversion Data
Device Write Command Register Addressed R/W Register Address Data 32-Bit Write Command
Slave Write 1 FRMCTL 1 000 1010 0001 1111 1111 0110 0001 0000 0x8A1FF610
Write 2 CMREFCTL 1 000 0101 0000 0000 0000 0000 0000 0100 0x85000004
Write 3 ECGCTL 1 000 0001 1110 0000 0000 0000 1101 1110 0x81E000DE
Master Write 4 FRMCTL 1 000 1010 0001 1111 1001 0110 0000 0000 0x8A1F9600
Write 5 CMREFCTL 1 000 0101 1110 0000 0000 0000 0000 1011 0x85E0000B
Write 6 ECGCTL 1 000 0001 1110 0000 0000 0100 1011 1110 0x81E004BE
Master
and
Slave
Write 7 FRAMES 0 100 0000 0000 0000 0000 0000 0000 0000 0x40000000