Cortex-M7 (low-power core)

The Cortex-M7 core is the auxiliary core on the PicoCoreMX8MP used for low-power operations, i.e. whenever the satellite is not above a desired observation site. It is responsible for communicating with a GNSS module to acquire accurate time and position measurements, and it hosts a csp_proc server, which facilitates small libparam-native programmable procedures that can be sent to the M7 for execution. Furthermore, the CSP node that represents this core contains the wake_a53 param, which triggers a callback to wake the Cortex-A53 cores from low-power mode.

Parameters (libparam)

The following libparam parameters are exposed on the CSP node representing the M7 core:

Parameter Name	Type	Description
Application parameters
wake_a53	uint8	Send wake signal to A53 peer core
a53_status	uint8	A53 peer core status
tmu_reading	uint16	TMU temperature reading
gnss_lat	float	GNSS latitude
gnss_lon	float	GNSS longitude
gnss_age	uint32	GNSS fix age
gnss_date	uint32	GNSS date
gnss_time	uint32	GNSS time
gnss_speed	float	GNSS speed
gnss_alt	float	GNSS altitude
gnss_course	float	GNSS course
General purpose parameters
p_uint8	uint8	uint8 array (32)
p_uint16	uint16	uint16 array (32)
p_uint32	uint32	uint32 array (32)
p_uint64	uint64	uint64 array (32)
p_int8	int8	int8 array (32)
p_int16	int16	int16 array (32)
p_int32	int32	int32 array (32)
p_int64	int64	int64 array (32)
p_float	float	float array (32)
p_double	double	double array (16)
System registers
GPC__SLPCR	uint32	System low power control register
GPC__LPCR_A53_BSC	uint32	Basic Low power control register of A53 platform
GPC__LPCR_A53_AD	uint32	Advanced Low power control register of A53 platform
GPC__LPCR_M7	uint32	Low power control register of M7 CPU
GPC__MLPCR	uint32	Memory low power control register
GPC_PGC__A53SCU_PUPSCR	uint32	GPC PGC Up Sequence Control Register
GPIO1__DR	uint32	GPIO1 data register
GPIO1__GDIR	uint32	GPIO1 direction register (input/output)
GPIO2__DR	uint32	GPIO2 data register
GPIO2__GDIR	uint32	GPIO2 direction register (input/output)
GPIO3__GDIR	uint32	GPIO3 direction register (input/output)
GPIO4__GDIR	uint32	GPIO4 direction register (input/output)
GPIO5__GDIR	uint32	GPIO5 direction register (input/output)
MUB__SR	uint32	MU Status register
RDC__STAT	uint32	RDC Status register
TMU__TSCR	uint32	Sensor Calibration register
TMU__TRITSR	uint32	Immediate Temperature Site register n
TMU__TRATSR	uint32	Average Temperature Site register n

Application components

A visual representation of the components in the application running on the M7 core is shown in the 2 treemaps below. The ITCM is the memory that is used by the M7 core to store instructions, and the DTCM is the memory that is used to store data. Both are limited to 128 KB.