User's Manual

Preliminary Specification Number : SP-ABZ-F
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11. Reference circuit
U4
LoRa module
PA12/USB_DP
1
PA11/USB_DM
2
GND
3
VDD_USB
4
VDD_MCU
5
VDD_RF
6
GND
7
DBG_SX1276_DIO2
8
DBG_SX1276_DIO3
9
SX1276_DIO4
10
DBG_SX1276_DIO5
11
DBG_SX1276_DIO1
12
DBG_SX1276_DIO0
13
PB15/SPI2_MOSI
14
PB14/SPI2_MISO
15
PB13/SPI2_SCK
16
PB12/SPI2_NSS
17
PA10/USART1_RX
18
PA9/USART1_TX
19
PA8/MCO
20
PA5/ADC5/DAC2
21
PA4/ADC4/DAC1
22
PA3/ADC3
23
PA2/ADC2
24
GND
25
ANT
26
GND
27
DBG_CRF1
28
DBG_CRF3
29
DBG_CRF2
30
STSAFE_nRST
31
VREF+
32
PA0/WKUP1
33
MCU_nRST
34
PB8/I2C1_SCL
35
PB9/I2C1_SDA
36
PB2/LPTIM1_OUT
37
PB7/LPTIM1_IN2
38
PB6/LPTIM1_ETR
39
PA13/SWDIO
41
PA14/SWCLK
42
BOOT0
43
GND
44
PB5/LPTIM1_IN1
40
PH1-OSC_OUT
45
PH0-OSC_IN
46
TCXO_OUT
47
VDD_TCXO
48
GND
49
GND
50
GND
51
GND
52
GND
53
GND
54
GND
55
GND
56
GND
57
C3 10uF
C5 0.1uF
J1
1
1
2
2
3
3
4
4
5
5
6
6
Notes for VREF+ 1. VREF+ can be grounded when ADC and DAC are not active. 2. VREF+ can be connected to a separate voltage which is between 1.8V and VDD for better accuracy on low-voltage inputs and outputs of ADC and DAC.
C6
1uF
VDD_TCXO
Button
1 2
C7 0.1uF
VDD
R2
10K
J2
2 3 4
1 5
SMA connector to 868MHz/915MHz Antenna
C4 1uF
VDD
VDD_USB
C8 C9
SWD connector
L1
VDD
R1
10K
for VDD_TCXO connection Option1: Connect VDD_TCXO to VDD Option2: Connect VDD_TCXO to PA12 to make sure MCU can control TCXO on/off
VREF+
C1 10uF
C2
0.1uF
Optional