Introduction¶
LimePSB RPCM Board Key Features¶
The LimePSB RPCM is carrier board for Raspberry Pi Compute Module 4 (CM4) and mPCIe card (by default LimeSDR XTRX board). LimePSB RPCM carrier board provides a hardware platform for developing and prototyping high-performance designs based on Raspberry Pi CM4, RF front end, clock network and mPCIe card. It allows user to use the board in SDR, LoRa and other applications.
LimePSB RPCM board features:
Connectors:
Raspberry CM4 connector (dual row)
USB 2.0 (Type-C) socket (USB boot and power delivery)
Dual USB 2.0 (type A) socket (downstream ports) or Front Panel USB 2.0 header (unpopulated)
Ethernet jack (Gigabit Ethernet with PoE)
mini PCIe x1 Gen 2 (5Gbps)
2x HDMI 2.0 receptacle (up to 4Kp60 supported)
2x 15-pin FPC connectors for MIPI DSI display and CSI camera
3.5 mm 4-pin jack for analog audio and composite video
uSD card socket
Nano-SIM socket
Coaxial RF (4x SMA female + 4x U.FL female) connectors for RF front end
Coaxial pass-through U.FL to external SMA connector
20-pin Raspberry CM4 GPIO header (3.3V)
14-pin Raspberry CM4 SYS header
5-pin front display connector (power, I2C, button)
Raspberry CM4 UART0 header (unpopulated)
2-pin and 4-pin FAN connector (5V default or 3.3V or VCC_INT voltage)
RF front end:
Configuration: MIMO (2x TRX, 2x RX)
LNAs, PAs, RF switches, power and mode control (TDD and FDD)
Miscellaneous:
Board temperature sensor
EEPROM
Secure key storage, shift registers
RTC, ADC
USB 2.0 hub
General user inputs/outputs:
4x general purpose Dual colour (RG) LEDs
20 pin CM4 GPIO header (3.3V)
Front button
Clock system:
30.72MHz (default) on board VCOCXO and 30.72/38.4/40.00MHz (optional) VCTCXOs
Possibility to tune on board XO by on-board DAC, by phase detector to match a reference clock input (PTP or external clock).
Reference clock/PPS input and output SMA connectors (EXT_SYNC_IN and EXT_SYNC_OUT)
Possibility to synchronize multiple boards using coaxial SMA connectors (EXT_SYNC_IN and EXT_SYNC_OUT)
Board size: 170mm x 110mm
Board power sources:
Barrel (9-14V, 2-3A)
USB Power Delivery (12V 1.5A or 2.5A)
PoE (12V, 2A)
For more information on the following topics, refer to the folowing documents:
Board Overview¶
The heart of the LimePSB RPCM carrier board is Raspberry PI Compute Module 4 which may be used to transfer digital data between the CM4 and mPCIe board while performing data processing. The block diagram for LimePSB RPCM board is as shown in Figure 3.
LimePSB RPCM board picture with highlighted connectors and main components are presented in Figure 4 and Figure 5.
Description of board components is given in the Table 1.
Miscellaneous devices |
||
---|---|---|
IC9 |
IC |
I²C temperature sensor LM75 |
IC10/IC11 |
IC |
I²C EEPROM Memory 128Kb (16K x 8), connected to RF transceiver I2C bus |
IC12/IC13 |
IC |
I²C secure key storage |
IC15/IC17 |
IC |
I²C Real time clock |
IC8 |
IC |
8 channel 12 bit ADC |
IC14, IC16 |
IC |
8 bit shift register |
IC19 |
IC |
USB2.0 HUB |
IC20 |
IC |
USB switch |
J26, J25 |
Pin header |
2-pin and 4-pin FAN connector (5V default or 3.3V or VCC_INT voltage) |
Configuration, Status, Setup Elements and GPIOs |
||
LED1, LED2, LED3, LED4 |
Red-green status LEDs |
User defined indication LED |
LED5 |
Red-green status LEDs |
Raspberry CM4 status |
LED6 |
Green status LED |
Power indication LED |
J14 |
Header |
14-pin Raspberry CM4 SYS header |
J5 |
Header |
Power control and PG status |
J6 |
Header |
Wireless LAN and Bluetooth control |
J10 |
Header |
20-pin CM4 GPIO header |
RF front end |
||
IC32, IC33 |
IC |
PA SBB-5089 |
IC36, IC37 |
IC |
LNA SPF5043Z |
IC30, IC31, IC34, IC35 |
IC |
RF switch SKY13286 |
Communication Ports |
||
J1, J2 |
Connector |
Raspberry Pi CM4(L) connectors |
J11 |
Header |
Raspberry CM4 UART0 header (unpopulated) |
J8 |
Header |
5-pin front screen connector (power, I2C, button) |
J27 |
USB |
USB 2.0 (Type-C) socket |
J29 |
USB |
Dual USB 2.0 (Type-A) socket |
J9 |
Ethernet |
Gigabit RJ45 (Ethernet with magnetics) port |
J12, J13 |
HDMI |
HDMI 2.0 socket |
J17, J18 |
LVDS |
FPC 15-pin for display and camera |
J16 |
Audio/Video |
3.5 mm jack |
J7 |
SDIO |
Micro SD card holder |
J4 |
Nano-SIM |
Nano-SIM card holder |
J3 |
Mini PCIe |
Mini PCIe x1 expansion slot |
Clock Circuitry |
||
XO1 |
VCOCXO |
30.72 MHz VCOCXO |
XO2 |
VCTCXO |
30.72 MHz VCTCXO |
XO3 |
VCTCXO |
30.72 MHz VCTCXO |
XO4 |
VCTCXO |
40.00 MHz VCTCXO |
XO5 |
VCTCXO |
38.40 MHz VCTCXO |
IC27 (IC29) |
IC |
16 (8) bit DAC for XOs VC tuning |
IC25 |
IC |
Clock buffer |
IC28 |
IC |
Phase detector |
J32 |
SMA connector |
Reference clock input EXT_SYNC_IN |
J35 |
SMA connector |
Reference clock output EXT_SYNC_OUT |
J33 |
U.FL connector |
Reference clock output |
J22/J24, J23 |
Multiple |
Internal connector J22/J24 to external SMA J23 |
Power Supply |
||
IC45 |
IC |
Switching regulator ADP2386 (3.3V rail) |
IC46 |
IC |
Switching regulator ADP2386 (5.0V rail) |
IC47 |
IC |
Linear regulator AP7361-FGE (3.3V rail) |
IC49 |
IC |
Linear regulator AP7361-FGE (1.5V rail) |
IC48 |
IC |
Voltage reference AS431ANTR-G1 (2.5V rail) (unpopulated) |