LX7720 Daughter Board User's Manual
FMC Connection to FPGA Evaluation Boards
© 2023 Microchip Technology Inc. LX7720 Daughter Board User Guide rev 3.1 - page 3
1 FMC Connection to FPGA Evaluation Boards
The LX7720-DB uses an HPC-FMC, J10, for signals to and from an external FPGA board, discussed in detail in Section 7
on page 17. Pinouts and FPGA resource allocations are provided for the following FPGA boards' HPC1-FMC connector:
• The RTG4 FPGA DEV-KIT (Table 17 on page 19)
• The PolarFire FPGA MPF300-EVAL-KIT (Table 17 on page 19)
• The RT PolarFire FPGA RTPF-DEV-KIT (Table 18 on page 20)
• The SmartFusion2 SoC FPGA M2S150-ADV-DEV-KIT (Table 19 on page 20)
2 Linker Adaptors to MCU Evaluation Boards
The 2x20 pin 0.1" pitch pin header, J20, provides the same signals as the HPC-FMC discussed above. Section 6 on page
16 details J20's pinout. The LX7720-DB includes linker adaptors for direct interconnection to MCU controller boards:
• The SAMRH71-EK linker (section 8 on page 22) routes J20 signaling to a SAMRH71F20-EK evaluation kit for the
SAMRH71F20 MCU. Table 21 on page 23 provides the pinout and MCU resource allocation. The kit comprises a
linker board connecting a SAMRH71F20-EK to the LX7720MLF-EVB, a small board with switches, and a ribbon cable:
The linker board connects signals from the SAMRH71F20-EK's 0.1" headers J24 and J30 to J20
▫ All four LX7720 half-bridges are routed to the MCU PWM outputs, for BLDC and stepper compatibility
▫ 3 of the 4 motor phase current ∆Σ serial streams (SNS_OUT_A, B, and C) are routed to MCU TCLK inputs
▫ Two LX7720 bi-level (comparator) outputs are routed to MCU QDEC TIO inputs for quadrature encoder use
▫ The resolver/LVDT transformer primary differential drive (DMOD_IN_P, DMOD_IN_N) and associated ADC
Σ-Δ modulators ADC1, ADC2, and ADC3 are not routed to the MCU, but brought out to test point holes
The switch board connects to GPIOs on SAMRH71F20-EK's 0.1" header J25 via a 20 way ribbon cable. The
SAMRH71F20 optionally uses GPIOs to monitor five push switches and operate two LEDs as status indicators
• The SAMRH71-TFBGA-EK linker (section 8 on page 22) routes J20 signaling to a SAMRH71-TFBGA-EK evaluation
kit for the SAMRH71F20 MCU. The same signals are routed as for the SAMRH71-EK linker discussed above:
The linker board connects signals from the SAMRH71-TFBGA-EK's 0.1" headers J5 and J7 to J20
▫ All four LX7720 half-bridges are routed to the MCU PWM outputs, for BLDC and stepper compatibility
▫ 3 of the 4 motor phase current ∆Σ serial streams (SNS_OUT_A, B, and C) are routed to MCU TCLK inputs
▫ Two LX7720 bi-level (comparator) outputs are routed to MCU QDEC TIO inputs for quadrature encoder use
▫ The resolver/LVDT transformer primary differential drive (DMOD_IN_P, DMOD_IN_N) and associated ADC
Σ-Δ modulators ADC1, ADC2, and ADC3 are not routed to the MCU, but brought out to test point holes
The switch board connects to GPIOs on SAMRH71-TFBGA-EK 0.1" header J9 via a 20 way ribbon cable.
• The SAMRH707-EK linker (section 9 on page 28) routes J20 signaling to a SAMRH707-EK evaluation kit for the
SAMRH707F18 MCU. Table 11 on page 30 provides the pinout and MCU resource allocation.
The linker board connects signals from SAMRH707-EK 0.1" headers J18, J19, and J20 to J20
▫ All four LX7720 half-bridges are routable to the MCU PWM outputs, for BLDC and stepper compatibility
▫ The resolver/LVDT transformer primary differential drive (DMOD_IN_P, DMOD_IN_N) is routable to the 4th
pair of MCU PWM outputs instead of the 4th LX7720 half-bridge. This eases operation of either a 3-phase
BLDC plus resolver/LVDT, or a bipolar stepper motor without resolver/LVDT without external wiring
▫ 3 of the 4 motor phase current ∆Σ serial streams (SNS_OUT_A, B, and C) are routed to MCU TCLK inputs
▫ All 4 phase current ∆Σ serial streams (SNS_OUT_A x) and the 3 resolver/LVDT Σ-Δ serial streams (ADCx)
are processed on the linker board by RLC passive filters ((Figure 28 on page 28). This allows any of the
LX7720's ∆Σ serial streams to be acquired by MCU ADC channels instead of by DSP firmware
▫ Two LX7720 bi-level (comparator) outputs are routed to MCU QDEC TIO inputs for quadrature encoder use
3 Documentation and Support
The USB stick (contents also available here) included with the LX7720-DB includes the following:
• RTG4 targeted binaries and Libero source projects for the following motor control systems (see separate User Guide):
BLDC motor, either sensorless or using a resolver
Stepper motor
• GUI binaries and source for sensorless or resolver-feedback BLDCs (BLDC motor v4.1) and stepper motors (Stepper
motor v1.0) for the setup of LX7720-DB connected to an RTG4 DEV-KIT
• SAMRH71F20 targeted binary and MPLAB source project for a BLDC motor with encoder (see separate User Guide)
• Altium schematic and PCB files for the LX7720-DB and the linker boards
• FPGA IP user guides on the USB stick are from https://www.microchip.com/en-us/products/fpgas-and-plds/ip-core-
tools. The Microchip Libero library offers IP that can be downloaded under the Libero license
• For application support, use the Microchip Technical Support Portal
