A UART/SPI Monitor For Your MicroPart 2
by Mark Mitchell
Having visibility into an SPI bus is a very convenient and sometimes necessary
feature when working with microcontrollers. Last month, we started a project that
provides the desired “peek under the hood” with a tool that accesses and excites the
SPI bus and also provides a UART logic level shifter for easy connection to a serial
port from your micro.
Our goal this month is to finish off the monitor by
updating a few features and to put it in a useable housing.
First, we’ll wrap up the hardware for the project by putting
it in a box. The enclosure will make the unit more robust
and attractive, thus providing a handy test tool for the lab.
Next, we will implement a FIFO (First In First Out)
FIGURE 1. Top of
the modified board.
36 SERVO 06.2011
buffer in the firmware to enhance the speed and usability
of the board. The FIFO will allow longer data sequences to
be monitored and allow better speed performance on the
monitor’s SPI port. SPI has several flavors that are used by
different devices. These are referred to as the operating
modes. We will add the ability to configure these modes so
that most SPI devices can be used.
FIGURE 2. Bottom
of the modified board.