Control Registers
1212
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Multi-Buffered Serial Peripheral Interface Module (MibSPI) with Parallel Pin
Option (MibSPIP)
24.9.45 SPI Extended Prescale Register 2 (EXTENDED_PRESCALE2 for SPIFMT2 and
SPIFMT3)
This register provides an extended Prescale values for SPICLK generation to be able to interface with
much slower SPI Slaves. This is an extension of SPIFMT2 and SPIFMT3 registers. For example,
EPRESCALE_FMT3[7:0] of EXTENDED_PRESCALE2 and PRESCALE3 of SPIFMT3 register will always
reflect the same contents. Similarly, EPRESCALE_FMT2[7:0] and PRESCALE2 of SPIFMT2 reflect the
same contents.
Figure 24-75. SPI Extended Prescale Register 2 (EXTENDED_PRESCALE2 for SPIFMT2 and
SPIFMT3) [offset = 13Ch]
31
27
26
16
Reserved
EPRESCALE_FMT3
R-0
R/WP-0
15
11
10
0
Reserved
EPRESCALE_FMT2
R-0
R/WP-0
LEGEND: R/W = Read/Write; R = Read only; WP = Write in privilege mode only; -
n
= value after reset
Table 24-53. SPI Extended Prescale Register 2 (EXTENDED_PRESCALE2) Field Descriptions
Bit
Field
Value
Description
31-27
Reserved
0
Reads return 0. Writes have no effect.
26-16
EPRESCALE_FMT3
0-7FFh
EPRESCALE_FMT3. Extended Prescale value for SPIFMT3. EPRESCALE_FMT3
determines the bit transfer rate of data format 3 if the SPI/MibSPI is the network master.
EPRESCALE_FMT3 is use to derive SPICLK from VCLK. If the SPI is configured as
slave, EPRESCALE_FMT3
does not need
to be configured. These
EPRESCALE_FMT3[7:0] bits and PRESCALE3 bits of SPIFMT3 register will point to the
same physically implemented register. The clock rate for data format 1 can be calculated
as:
BR
Format3
= VCLK / (EPRESCAL 1)
Write: This register field should be written if a SPICLK prescaler of more VCLK/256 is
required. This field provides a prescaler of up to VCLK/2048 for SPICLK. Writing to this
register field will also get reflected in the PRESCALE3 bits of SPIFMT3 register.
Read: Reading this field will reflect the PRESCALE value based on the last written
register field, that is, EXTENDED_PRESCALE3[26:16] or SPIFMT3[15:8] register.
Note: If Extended Prescaler is required, it should be ensured that
EXTENDED_PRESCALE2 register is programmed after SPIFMT3 register is
programmed. This is to ensure that the final SPICLK prescale value is controlled by
EXTENDED_PRESCALE2 register when a prescale of more 256 is intended on
SPICLK. Writing to PRESCALE3 field of SPIFMT3 will automatically clear
EPRESCALE_FMT3[10:8] bits to 000 so that the integrity of PRESCALE value is
maintained.
15-11
Reserved
0
Reads return 0. Writes have no effect.