90 Silicon chip Australia’s electronics magazine siliconchip.com.au
interface. This is provided by an ST-
Micro 8L151G 8-bit ultra-low-power
microcontroller that’s inside the 21 x
18 x 2.5mm shield on the top of the
PCB, along with the SX1278 chip.
The result is that it’s somewhat eas-
ier to program and use this module, as
we’ll see shortly.
We couldn’t find an internal circuit
diagram for the E32-TTL-100 module,
but there is a 14-page data sheet avail-
able for the module which describes
how to program and use it: siliconchip.
com.au/link/aao4
The simplest way to use the E32-
TTL-100 module is to hook it up di-
rectly to a PC via a CP2102-based USB-
to-UART bridge. eByte makes a custom
bridge module for this job, called the
E15-USB-T2 serial port adaptor.
Measuring just 26 x 20mm, this PCB
has a type-A USB plug at one end and
a 7-pin SIL socket in the centre, into
which the E32-TTL-100 module can
be plugged (see photo above).
The E15-USB-T2 adaptor module is
available from AliExpress, Alibaba and
other suppliers, for less than $3.50. It
has a 3.3V regulator on the underside
plus a 3-pin SIL header on the top to
allow you to select either 5V or 3.3V as
the supply for the E32-TTL-100 mod-
ule using a jumper shunt.
You can find four page data sheet on
the E15-USB-T2 at http://www.cdebyte.com/
en/pdf-down.aspx?id=761
There’s also another pair of 2-pin
SIL headers with jumper shunts to al-
low the voltages on the E32-TTL-100
module’s M0 and M1 mode select
pins to be set to either logic high or
low. There’s even a pair of tiny SMD
LEDs, indicating its status. Fig.2 shows
how the E32-TTL-100 and E15-USB-
T2 modules connect together.
Note that if your PC doesn’t have a
VCP (virtual COM port) driver already
installed for CP2102 based bridges,
you’ll need to install one to use this de-
vice (Windows 10 usually has this pre-
installed). This driver can be down-
loaded from the Silicon Labs website
(siliconchip.com.au/link/aalb).
You can then program the mod-
ule and communicate via the LoRa
modules is by using a serial monitor-
ing application like AccessPort 1.37.
This can be downloaded free fromhttps://accessport.en.lo4d.com/ Once
installed, it provides a very intuitive
way to either send or receive data to/
from the E32-TTL-100 module.
You can communicate using either
hexadecimal numbers or text charac-
ters; it’s best to use hex codes during
the initial set-up (with the M0 and M1
jumpers on the E15 bridge module un-
plugged), and then text characters for
normal airborne communication (with
the M0 and M1 jumpers fitted). Table 1
is a summary of the basic E32-TTL-100
set-up steps.
Once the module is set up, connect
a suitable antenna to the SMA socket
and then fit the M0 and M1 jumperFig.2: connection diagram for the E15-USB-T2 and E32-TTL-100 modules.
Attaching only jumper M1 puts the module into power-saving mode (closes
RXD), while only M0 starts wake-up mode (opens RXD).The E15-USB-T2 serial port adaptor module connects
to the E32-TTL-100 via a 7-pin female header and lets
you plug the module into a computer and program it
using software such as AccessPort.