Article

Bluetooth with the ATM18

The Vikings Are Coming!

Since its introduction in 2001, Bluetooth has developed into an essential standard for wireless links between devices. Using an inexpensive serial module, we can add Bluetooth functionality to our ATM18 board. Naturally, the example software written in C can also be adapted for use with other ATmega boards.

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Materials

080948-PCB.pdf

080948-11.zip

Extra info / Update

BTM-222 Bluetooth module features
Certified for Bluetooth Version 2.0 and EDR
Direct line-of-sight range with lambda/4 antenna (31 mm): 80–150 m (depending on weather conditions)
Transmit power (Class 1): 18 dBm max.(63.1 mW into 50 Ohm)
Low power consumption (hold, sniff, park, and deep sleep mode)
Supply voltage: 3.0–3.6 V
Full Bluetooth data rate via UART
Supports up to seven ACL links and three SCO links
Supports enhanced data rate (EDR) for both modulation modes (2 Mbps and 3 Mbps)
SPP firmware with AT commands
Dimensions (mm): 28.2 x 15.0 x 2.8

Component list

R1–R8 = 1kOhm SMD 0805
C1,C3,C4 = 100nF SMD 0805
C2 = 10µF 10V SMD 1206
Semiconductors
D1 = LED, red, SMD 0805
D2 = LED, green, SMD 0805
T1–T4 = BC847, SMD (SOT-23)
IC1 = BTM-222, Bluetooth module, from Rayson Technology*
IC2 = LF33C or LF33CDT, DPAK-case, (e.g. Farnell # 1087187)
K1 = 6-way socket strip, right angled
JP1 = 3-pin header with jumper (or wire link)
PCB # 080948-1*

Addiional parts if IC1 = BTM-220 instead of BTM-222
Resistors
All SMD 0805
R9 = 47kOhm
R10 = 22kOhm
R11 = 1.5kOhm
R12,R13 = 27
Capacitors
C5,C6 = 100nF SMD 0805
Inductor
L1 = 2200Ohm @ 100MHz, e.g. Murata DLW31SN222SQ2L (Farnell # 515599)
Miscellaneous
K2 = USB plug, type A, SMD, e.g. Lumberg 2410 07 (Farnell # 1308875)