Remote Control¶

Before diving into how the remote control for the Retina works, it has to be mentioned that we offer a Python controller class, WebSQControl, to facilitate easy remote control via Python. The latest version, along with full documentation, is available in the Help section of the user interface. If your goal is to get started quickly we would recommend you access this class and look at the examples here.

Methods of communication¶

JSON RPC¶

In order to send commands to the Retina driver we make use of the JSON RPC protocol. Commands in this format can be send to the API endpoint: [Driver IP]/api. This allows for communication with the driver, independent of platform or language. A request object in a JSON RPC command is expected to have the following format:

{
    "method": "<method name>",
    "params": "<parameters for the method>",
    "jsonrpc": "2.0",
    "id": "<identifier>"
}

A full list of methods, with expected parameters and responses can be found in the appendix here.

Websocket (Readout only)¶

The websocket outputs a direct stream of bytes which gives the most efficient way to readout data by far. You can access the websocket by listening to the following endpoint: [Driver IP]/counts.

The messages which are send here consist of 32 bytes, and structured as show in table Table: Channel Unit message structure. Every measurement interval of 10ms, these messages will be bundled and send to the websocket as one byte string. These messages will have to be split up again for readout.

WebSQControl Examples¶

We include a few examples of how to use the WebSQControl. The latest versions of these will be available in the help section of the user interface. We explore a few basic functionalities.

Collecting Counts¶

This example collects counts from the websocket for 2 seconds, with an interval of 0.1 seconds. This should return a list of the countrates for each channel every 0.1 seconds.

from WebSQController import WebSQController

# Please change this to be the IP address of the driver in your network
websq_domain = 'http://192.168.10.10/'

sq = WebSQController(websq_domain)

# Collects counts for 2 seconds every 0.1 seconds.
counts = sq.collectCounts(2, 0.1)
print(counts)

IV Sweeping¶

This example performs and IV sweep and prints the result for the first channel.

from WebSQController import WebSQController

# Please change this to be the IP address of the driver in your network
websq_domain = 'http://192.168.10.10/'

sq = WebSQController(websq_domain)

traces = sq.sweepIv(0, 50, 1, 100)

channels = list(traces.keys())
first_channel = channels[0]

print(f"Data for channel {first_channel}:")
print("Bias Current (uA):")
print(traces[first_channel]['biasI'])
print("Monitor Voltage (V):")
print(traces[first_channel]['monitorV'])

Setting the Bias Current¶

This is an example of how to set values on the driver for a specific channel.

from WebSQController import WebSQController

# Please change this to be the IP address of the driver in your network
websq_domain = 'http://192.168.10.10/'
sq = WebSQController(websq_domain)

print("Setting the bias current to 20 uA, for channel 1")

sq.setBiasI(20e-6, channels=[1])

print("Getting the bias current value of channel 1:")
print(sq.getBiasI(channels=[1]))