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Requests can be issued to the Notecard over USB
, UART
, or I2C
. The
Serial UART
interface is fixed at a baud rate of 9600, with eight data bits,
no parity bit, and one stop bit (9600/N-8-1).
The Notecard I2C
interface is available at address 0x17
, but can be
reconfigured using a card.io
request. This interface implements a straightforward serial over I2C
protocol.
The simplest way to initiate a connection with the Notecard from firmware is with one of our firmware libraries. Using this approach, you can initialize the Notecard over the appropriate interfacing using a few lines of code. For instance, with Serial:
Or with I2C
:
If NOT using a Notecard firmware library, you may unintentionally send requests to the Notecard so fast that you overflow the 1500 byte buffer used to receive data (whether it be I2C, Serial, or UART). The solution is to pause 250 ms after every 250 bytes sent and ensure the total size of each NDJSON object sent is no more than 8KB.
Alternatively, it's possible to manually communicate with the Notecard
over Serial in firmware using language-equivalent print()
and read()
functions.
If, on the other hand, you wish to use I2C
without one of our firmware
libraries, you'll need to write your own logic for writing to and reading from
the bus. Your approach will vary from one language to the next, but you should
use the existing implementations and the
Serial-over-I2C Protocol Guide
for reference.