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Swiss Pi
A Swiss army knife for the Raspberry Pi
The Raspberry Pi single board computer (SBC) was launched in the spring of 2012, and now — over four years later — it is still extremely popular. Not content to rest on their laurels, the Raspberry Pi Foundation has kept busy with upgrades and rolled out the third version last February. One thing that has certainly contributed to the popularity of the Raspberry Pi is that the 40-pin GPIO connector makes it very easy to extend the basic board with custom modules. We felt challenged.
Materials
Extra info / Update
16 GPIO lines with configurable pull-up, 5-V signal levels
16 12-bit PWM channels, configurable 24–1526 Hz, 5-V signal levels
4 connectors for remote control servos (shared with PWM channels 0 to 3) and supply voltage connector
8 12-bit ADC inputs, range 0–4.096 V
Half-duplex RS-485 interface compliant with TIA/EIA 485A standard, with ESD protection
Precise real time clock with battery backup, 3 ppm accuracy
I2C extension connector, 5-V signal levels
ID EEPROM
16 12-bit PWM channels, configurable 24–1526 Hz, 5-V signal levels
4 connectors for remote control servos (shared with PWM channels 0 to 3) and supply voltage connector
8 12-bit ADC inputs, range 0–4.096 V
Half-duplex RS-485 interface compliant with TIA/EIA 485A standard, with ESD protection
Precise real time clock with battery backup, 3 ppm accuracy
I2C extension connector, 5-V signal levels
ID EEPROM
Component list
Component List
Resistors
Default: SMD 0805
R1 = 4.7Ohm
R2,R3 = 10Ohm high pulse loading
R4 = 100Ohm =250mW
R5 = 120Ohm =250mW
R6–R12 = 1kOhm
R13 = 2.2kOhm
R14,R15 = 3.9kOhm
R16–R19 = 4.7kOhm
R20,R21 = 10kOhm
Coapacitors
C1–C11 = 100nF, 0805
C12,C13,C14 = 1µF, 1206
C15 = 10µF, 1206
Semiconductors
T1, T2 = BSN20
IC1 = 12MHz oscillator block, SMD, type LFSPXO018037
IC2 = SN74LVC1T45DBVR
IC3 = ATtiny45-20SU, programmed
IC4 = SN65HVD3085EDG4
IC5 = SN74LVC1G00DBVR
IC6 = PCF2129AT
IC7 = BR24G32FJ-3GTE2, 32 Kbit I2C EEPROM
IC8 = MAX11614EEE+
IC9 = PCA9685PW,112
IC10 = MCP23017-E/SS
ZD1 = CDSOT23-SM712, 12V Transient Voltage Suppressor
Miscellaneous
F1 = 16V 0.35A Polyswitch type 1206L035/16YR
B1 = 2032 button cell holder
K1 = 40-way (2x20) socket, 0.1’’ pitch
K2 = 3-way PCB screw terminal block, RS-485-bus, 5mm pitch
K3 = 2-way PCB screw terminal block, 5mm pitch
K4 = 4-pin pinheader, 0.1’’ pitch
K5 = 2-pin pinheader, 0.1’’ pitch
ADC = 10-pin (2x5) pinheader, 0.1’’ pitch
PWM_A, PWM_B = 10-pin (2x5) pinheader, 0.1’’ pitch
GPIO_A, GPO_B = 10-pin (2x5) pinheader, 0.1’’ pitch
SERVO_1 – SERVO_4 = 3-pin pinheader, 0.1’’ pitch
JP1–JP3 = 2-pin pinheader, 0.1’’ pitch, with jumper
Resistors
Default: SMD 0805
R1 = 4.7Ohm
R2,R3 = 10Ohm high pulse loading
R4 = 100Ohm =250mW
R5 = 120Ohm =250mW
R6–R12 = 1kOhm
R13 = 2.2kOhm
R14,R15 = 3.9kOhm
R16–R19 = 4.7kOhm
R20,R21 = 10kOhm
Coapacitors
C1–C11 = 100nF, 0805
C12,C13,C14 = 1µF, 1206
C15 = 10µF, 1206
Semiconductors
T1, T2 = BSN20
IC1 = 12MHz oscillator block, SMD, type LFSPXO018037
IC2 = SN74LVC1T45DBVR
IC3 = ATtiny45-20SU, programmed
IC4 = SN65HVD3085EDG4
IC5 = SN74LVC1G00DBVR
IC6 = PCF2129AT
IC7 = BR24G32FJ-3GTE2, 32 Kbit I2C EEPROM
IC8 = MAX11614EEE+
IC9 = PCA9685PW,112
IC10 = MCP23017-E/SS
ZD1 = CDSOT23-SM712, 12V Transient Voltage Suppressor
Miscellaneous
F1 = 16V 0.35A Polyswitch type 1206L035/16YR
B1 = 2032 button cell holder
K1 = 40-way (2x20) socket, 0.1’’ pitch
K2 = 3-way PCB screw terminal block, RS-485-bus, 5mm pitch
K3 = 2-way PCB screw terminal block, 5mm pitch
K4 = 4-pin pinheader, 0.1’’ pitch
K5 = 2-pin pinheader, 0.1’’ pitch
ADC = 10-pin (2x5) pinheader, 0.1’’ pitch
PWM_A, PWM_B = 10-pin (2x5) pinheader, 0.1’’ pitch
GPIO_A, GPO_B = 10-pin (2x5) pinheader, 0.1’’ pitch
SERVO_1 – SERVO_4 = 3-pin pinheader, 0.1’’ pitch
JP1–JP3 = 2-pin pinheader, 0.1’’ pitch, with jumper
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