HardLabs

Walky Talky

zmuhammad07·Walky_Talky·Hardware/WalkieTalkie.kicad_pcb

Walky Talky PCB layout, top view — open source STM32 board by zmuhammad07

About the Walky Talky PCB

Walky Talky is an open source STM32 PCB design by zmuhammad07, published on GitHub under the MIT license. It is a 2-layer board measuring 57.1 × 59.6 mm, with 45 components from 29 distinct parts.

Its main chip is the STM32F446RETx, from the STM32 family. Other key parts include the LM1117DT-ADJ, PAM8403D and KY-040. By type, the board carries 20 capacitors, 6 connectors, 5 resistors, 4 ICs, 2 switches and 1 module.

It belongs with the audio and rf & radio designs in this gallery.

From the project

Walky-Talky — LoRa voice communication system built on STM32 with a custom KiCad PCB. Features I2S digital mic input (INMP441), Codec2 voice compression (96kbps → 1.2kbps), RYLR998 LoRa RF at 915MHz, 12-bit DAC audio output, and FM-style channel selection via rotary encoder. All peripheral I/O driven by STM32 HAL DMA. Work in progress.

Walky-Talky is a custom STM32-based digital voice communication system built for long-range, low-bandwidth voice transmission over LoRa RF.

The project combines embedded firmware development, custom PCB design in KiCad, digital signal processing, and wireless communication into a fully self-contained handheld device.

Voice audio is captured using an INMP441 I2S microphone, compressed in real time using the Codec2 low-bitrate voice codec, and transmitted through a RYLR998 LoRa module operating at 915 MHz. On the receiving side, audio is decoded and played back through a 12-bit DAC and…

Walky Talky, from the project README
From the project README

Main components on the Walky Talky

STM32F446RETxLM1117DT-ADJPAM8403DKY-040

Walky Talky bill of materials (BOM)

45 components, 29 distinct parts.

QtyPartRefs
1
STM32F446RETx
U1
1
LM1117DT-ADJ
U2
1
PAM8403D
U3
1
KY-040
U4
1
~
M1
1
8MHz
Y1
1
USB_B_Micro
J1
2
Conn_01x04_Pin
J2, J3
3
Conn_01x01_Pin
J4, J5, J6
1
R
1k1
1
R2
10k1
1
R1
10k2
1
Speaker
LS1
1
SW_SPDT
SW1
1
SW_Push
SW3
1
RED
D1
1
120R
FB1
6
100n
C1, C2, C3, C4, C5, C10
3
10u
C6, C13, C18
1
10n
C7
Show 9 more
QtyPartRefs
4
1u
C8, C9, C19, C20
2
20p
C11, C12
1
100u
C14
1
2.2u
C15
2
0.1u
C16, C17
1
240
R1
1
390
R2
1
100k
R3
2
1k
R4, R5

Walky Talky design files

The KiCad project lives in the zmuhammad07/Walky_Talky repository on GitHub; these links point at the commit this page was built from.

Walky Talky: common questions

What microcontroller does the Walky Talky use?

The Walky Talky is built around the STM32F446RETx, from the STM32 family.

How big is the Walky Talky PCB?

The Walky Talky measures 57.1 × 59.6 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Walky Talky?

45 components, from 29 distinct parts. The full bill of materials is listed on this page.

Where can I download the Walky Talky design files?

From the zmuhammad07/Walky_Talky repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the Walky Talky design in my own project?

Yes, under the terms of its MIT license, which zmuhammad07 chose for the repository.

Can I test firmware for the Walky Talky without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug STM32 firmware against it before you order a PCB.

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