Libraries
Background
lpcSysIO.c – system-dependent core functions
These are processor-specific functions for Tollos.They should not normally be used directly by applications.
| Functions | |
|---|---|
| sysFeedDogIO | feed the watchdog (if started) |
| sysInitProcIO | initialize processor base function [startup] |
| sysIRQIO | enable or disable an interrupt |
| sysPowerIO | set a power mode and wait for interrupt |
| sysQueryIO | query a system item |
| sysSetIO | set a system item |
sysFeedDogIO – feed the watchdog (if started)
void sysFeedDogIO(void);
Once the watchdog has been started, this function is called to reset its counter and prevent a Watchdog Reset. If called before the watchdog is started it has no effect.
sysInitProcIO – initialize processor base function [startup]
int sysInitProcIO(void);
returns 0 if OK, −1 if error (but probably cannot recover)
This must be called before any other sysIO functions; it:
– initializes the processor [SystemInit or equivalent]
– sets the system core clock frequency (processor speed)
– maps the vector table to the start of RAM
Assumptions (cases catered for):
– there is either an external crystal or oscillator, so &chipCrystal will be non-zero
– speed will be set to highest of 48, 72, or 96 MHz if possible to allow setting of USB 48 MHz [in future it will make more sense to use PLL1 for USB, but needs some research to ensure this does not exclude devices; also the current approach keeps the code parallel with STM32]
– chipMaxClock will always be at least twice the external clock
– main oscillator is 2 -> 20 MHz (could be raised to 25 MHz using OSCRANGE bit)
sysIRQIO – enable or disable an interrupt
int sysIRQIO(int index, flag enable, uint level);
index – vector table index number (see sysVector; 0=WDT)
enable – 1 to enable, 0 to disable
level – priority level (if enabling) [0..15, 0=high]
returns 0 if OK, −1 if index is out of range [−14..max],
or −2 if level is too large
This function can be used to change the system vectors, such as SysTick, by using a negative index; these ‘core’ interrupts cannot be disabled.
sysPowerIO – set a power mode and wait for interrupt
void sysPowerIO(uint item);
item – a constant listed in tollosIO.h
Valid items are:
SYSTEM_DEEPPOWERDOWN – power off until Reset or RTC wake
SYSTEM_DEEPSLEEP – unclocked sleep
SYSTEM_POWERDOWN – power down (unclocked, slow start)
SYSTEM_SLEEP – idle (Wait For Interrupt)
Currently Tollos only uses SLEEP and DEEPPOWERDOWN.
sysQueryIO – query a system item
int sysQueryIO(uint item);
item – a constant listed in tollosIO.h
returns current value of the item; negative generally indicates failure
Valid items are:
SYSTEM_CLOCK – clock speed, Hz
SYSTEM_RESET – 0 if last reset was normal (POR or Reset pin), 1 if abnormal (Watchdog or Brownout)
SYSTEM_SYSTICK – SysTick interval in us
SYSTEM_WATCHDOG – Watchdog interval in us
sysSetIO – set a system item
int sysSetIO(uint item, int value);
item – a constant listed in tollosIO.h
value – value to set the item to
returns previous value of the item, or a negative number if an error or unknown
Valid items are:
SYSTEM_SYSTICK – SysTick interval in microseconds [>0, maximum depends on clock rate]
SYSTEM_WATCHDOG – Watchdog interval in microseconds [>=0, will be rounded up to 256 if less]