Output synchronization

In many situation, it's useful to synchronize the instant at which several outputs change. In AT1000 context, this is done with the Output hold mechanism. This mechanism allows for the writes commands to store the data in a buffer and only latch it to the physical pins of the AT1000 on a given synchronization edge. This is described with the example below, where outputs 1 and 2 need to be applied simultaneously (not sequentially, i.e. not one after the other):

Thanks to the hold and sync feature, the physical outputs do not update sequentially, as the commands are received by the AT1000 device, but on the opposite, the outputs are all updated after the sync command.

This output synchronization mechanism can be used to synchronize any variety of outputs:

• Digital outputs
• Analog outputs
• Outputs spanning across multiple daisy-chained devices

Note

For the output synchronization to work properly across multiple daisy-chained AT1000 devices, the AT1000 devices must be connected together with SMA cables using the SYNC-IN and SYNC-OUT SMA connector. Please refer to the product datasheet for more details on this connection.

The following code snippet shows a clear example of using the output synchronization:

NodeJS

const at1000 = require("at1000-node");
let devices = at1000.find_devices(5); // Find devices with a 5s timeout
let tester = devices[0]; // Open the first detected device

var test_pin5 = tester.digital_io(5);
var test_pin6 = tester.analog_io(6);
test_pin5.config_output(3.3, 0, false); 
test_pin6.config_output(2.5); 

//At this point in time, pin 5 reads 0V (digital 0)
//and pin 6 reads 2.5 volts (default value configured)

tester.hold_outputs();

test_pin5.write(1); 
test_pin6.write(9.5);

//At this point in time, pins 5 and 6 remain unchanged

tester.sync_outputs();

//At this point in time, pin 5 reads 3.3V (digital 1)
//and pin 6 reads 9.5 volts

Python

import at1000

# Find devices with a 5s timeout
devices = at1000.find_devices(5)
tester = devices[0]  # Open the first detected device

# Initialize GPIO 5 as a digital output and GPIO 6 as an analog output
test_pin5 = tester.digital_io(5)
test_pin6 = tester.analog_io(6)

# Configure GPIO 5 as a digital output with VOH = 3.3V, VOL = 0V, Default = 0V (LOW)
test_pin5.config_output(3.3, 0, false)

# Configure GPIO 6 as an analog output with a default value of 2.5V
test_pin6.config_output(2.5)

# At this point, pin 5 reads 0V (digital 0)
# and pin 6 reads 2.5V (default configured value)

tester.hold_outputs()  # Hold all outputs (changes won't take effect immediately)

# Set new output values (but they remain unchanged due to hold_outputs())
test_pin5.write(1)  # Request pin 5 to go HIGH
test_pin6.write(9.5)  # Request pin 6 to output 9.5V

# At this point, pins 5 and 6 remain unchanged

tester.sync_outputs()  # Synchronize all held outputs

# Now, pin 5 reads 3.3V (digital 1)
# and pin 6 reads 9.5V

The timing diagram below illustrates the effect of the hold and sync mechanism in the example snippet above: