siliconchip.com.au Australia’s electronics magazine May 2019 85
up a jumper wire to provide power to
the target board if necessary.
These pads are next to a DFN-8 chip
marked as U5, which is an MCP1727
voltage regulator.
The MCP1727 is capable of 1.5A,
although its power dissipation while
dropping 5V down to 3.3V would
bring it close to its thermal limit. In
any case, the typical 500mA limit of
the USB is sure to come into play long
before 1.5A is reached.
We 3D printed one of the Digi-Key-
designed cases, just to protect the unit
from damage.
Before we fitted the case, we not-
ed that the board appears to get quite
warm, even when idle.
As it is, we’ve left the lid off the
case for now, as we don’t want it to
overheat.
There appear to be some other
spare pads around the board, includ-
ing a pair of test points, another pair
marked RX0 and TX0, a small pitch
8-way header marked J2, a small pitch
2-way header marked J3 and a row of
five headers marked for synchronous
serial data of some sort.
None of these are noted in the infor-
mation sheet, so we can only specu-
late as to their purpose; they may be
for some as yet, unreleased feature.
Our verdict
The Snap Debugger/Programmer is
clearly an economy device intended to
be used with newer microcontrollers,
especially as it cannot work at all with
older devices that require high-voltage
programming.
Part support is still in progress. It
appears that many parts are still only
at the preliminary or beta stage of sup-
port, including those we have tested.
Nonetheless, we found that they
worked fine for programming and sim-There’s not much to the
Snap PCB. At left there are a few
support ICs, including an MCP1727 voltage
regulator. At centre is the SAM E70 processor, and at right is
the I/O pin interface circuitry. In comparison to the PICkit 4, it
lacks high voltage circuitry and target power supply amongst others.ple debugging.
If you are only working with 32-bit
PICs, the Snap appears to be an eco-
nomical option which provides prac-
tically all the upsides of the PICkit 4,
as long as you can live with providing
power to your target micro indepen-
dently of the programmer.
If you plan to use other devices, we
would not recommend it.
There are a small number of 8-bit
devices that it supports, such as the
16F1455, although some of these parts
offer high voltage and low voltage pro-
gramming.
This means the Snap programmer
would work if the chip is configured
with low voltage programming disa-
bled.
But keep in mind that the low-volt-
age programming can typically only
be disabled when using a high-voltage
capable programmer, so you should be
safe to use these parts with the Snap.
Overall, it’s ideal as an economical
first programmer, or as a second device
to carry with your laptop or notebook,
although we would recommend taking
a good look at the device support list
before making a decision. SCMPLAB SNAP vis MPLAB PICkit 4 comparison.