USB to I2C/SPI/UART Communications Gateway
for QMatrix and maXTouch
The B0700 communications gateway is designed to make it easy to connect a QMatrix or maXTouch controller IC to the PC, to monitor the touch signals, and view/change the configuration settings using QmBtn, Hawkeye and the maXTouch Object Server. It enables the QmBtn PC application to communicate with QMatrix touch ICs having an I2C interface, or having an SPI or UART interface that includes the DRDY signal. A touch development board fitted with a compatible bus connector or individual bus header pins can be directly connected to the communications gateway. B0700 is the main communications gateway supported by QmBtn.
An Atmel AT90USB646 microcontroller is at the heart of the board.
On-board level-shifters are fitted to the I2C, SPI and UART buses and enable communications with the target QMatrix IC operating at a voltage of 1V8, 2V4, 2V7, 3V3, or 5V. 10 Kohm pull-up resistors are included on the I2C lines, eliminating the need to add these to a target development board.
The I2C, SPI, and UART buses are routed to pin headers, and cables are provided for easy connection to the target touch board. A 3-pin header is used for the I2C bus, with a ground connection on the middle pin so that the cable can be connected either way round and thus allow the two I2C lines to be easily swapped.
The UART Rx and Tx lines share IO pins with two of the SPI lines.
The SPI bus header includes the DRDY signal, an essential communications pacing signal on some QMatrix ICs.
What is included ?