CCS/MSP432P401R: SPI communication problem for BSL

Part Number: MSP432P401R

Tool/software: Code Composer Studio

Hi，

I am using MSP‑EXP432P401R LaunchPad to develop application for BSL，the code to enter BSL as below

if (((input )& (BIT4)) == 0)
{
chkbsl = false;

MAP_Interrupt_disableMaster();
NVIC->ICER[0] = 0xFFFF;
NVIC->ICPR[0] = 0xFFFF;
NVIC->ICER[1] = 0xFFFF;
NVIC->ICPR[1] = 0xFFFF;

P1->OUT |= BIT0;
BSL_INVOKE(BSL_SPI_INTERFACE); // Call the BSL with given BSL parameters
} //BSL_UART_INTERFACE//BSL_SPI_INTERFACE

It ok that I test the code for UART. I sent BSL Version command and the response is fine. But when I entered SPI to test BSL version command  , I had the problem that I can not get response.

BSL Version Command : 0x80 0x01 0x00 0x19 0xE8 0x62

SPI Protocol

P1.4 STE Active Low

P1.5 CLK  CKPH = 0 CKPL = 1

P1.6 MOSI  MSB

P1.7 MISO Driven by Dummy 0xFF

Channel 1 : STE

Channel 2 : CLK

Channle 3 : MOSI

Channel 4 : MISO

BSL Version Command

When I transmitted Dummy 0xFF,  MISO did not response.

Zoom in MISO to find no response.

I don't know if anything is wrong,