USB-to-Serial Converters

FTDI Converters

FTDI (Future Technology Devices International Ltd.) is a popular and reputable designer and manufacturer of USB-to-Serial converters. They make a range of IC’s for this purpose, as well and manufacturing useful products which use these IC’s (such as USB-to-serial cables).

 

As of 2016, their IC’s are commonly found in good quality USB-to-serial hardware (more so than one of their main competitors, Prolific

Latency

USB-to-Serial converters introduce a fair bit of delays into serial communications. and depending on your latency requirements, this may effect your design.

The conditions which will cause an FTDI IC to send received serial data to the computer. Especially notice the 16ms "latency timer". Image from "FTDI - AN232B-04 - Data Throughput. Latency and Handshaking".
The conditions which will cause an FTDI IC to send received serial data to the computer. Especially notice the 16ms “latency timer”. Image from “FTDI – AN232B-04 – Data Throughput. Latency and Handshaking”.

The below image is a screenshot of FTDI RX/TX data captured with a logic analyser. The computer was running Java code which sent an 0x02 response as soon as it received an 0x01 byte.

FTDI RX and TX data captured by a logic analyser, with the computer running Java code which responds to 0x01 with 0x02. The "latency timer" on the FTDI IC has been reduced to 1ms, which gives a much  faster response time from the computer (about 1.5ms delay).
FTDI RX and TX data captured by a logic analyser, with the computer running Java code which responds to 0x01 with 0x02. The “latency timer” on the FTDI IC has been reduced to 1ms, which gives a much faster response time from the computer (about 1.5ms delay).

Drivers

FTDI provides the Java D2xx API for Android systems. The API is packaged into a file called d2xx.jar and can be downloaded from http://www.ftdichip.com/Android.htm.

Basic information on the driver software can be found at http://www.ftdichip.com/Support/Documents/TechnicalNotes/TN_147_Java_D2xx_for_Android.pdf.

Posted: July 12th, 2016 at 9:25 am
Last Updated on: July 13th, 2016 at 8:58 am