AN664 データシートの表示（PDF） - Silicon Laboratories

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AN664

PRECISION32™ CMSIS AND HAL USER’S GUIDE

Silicon Laboratories 

AN664

2.1.2.1. Using the MASK Definition

The HAL uses MASK definitions to clear or set bitfields in registers that support clear and set addresses. In these

cases, the address can be set equal to the mask directly to manipulate the bitfield. For example:

void

_SI32_USART_A_disable_rx_start_bit(SI32_USART_A_Type * basePointer)

{

//{{

basePointer->CONFIG_CLR = SI32_USART_A_CONFIG_RSTRTEN_MASK;

//}}

}

2.1.2.2. Using the SHIFT Definition

The HAL uses the SHIFT definition when a field value is passed to a routine. This allows the calling code to pass in

a raw value, and the HAL can handle the actual placement of the bitfield in the register. For example:

void

_SI32_USART_A_select_rx_stop_bits(SI32_USART_A_Type * basePointer,

SI32_USART_A_STOP_BITS_Enum_Type bits)

{

assert(bits < 4); // bits < 2^2

//{{

basePointer->CONFIG_CLR = SI32_USART_A_CONFIG_RSTPMD_MASK;

basePointer->CONFIG_SET = bits << SI32_USART_A_CONFIG_RSTPMD_SHIFT;

//}}

}

2.1.2.3. Using the Enumeration Definitions

The HAL uses the U32 enumeration definitions for the clear and set addresses or when accessing the entire

register. The HAL does not use the value definitions themselves whenever possible, since accessing a single

bitfield in a register is inefficient. For example:

void

_SI32_USART_A_enable_rx_error_interrupts(SI32_USART_A_Type *

basePointer)

{

//{{

basePointer->CONTROL_SET = SI32_USART_A_CONTROL_RERIEN_ENABLED_U32;

//}}

}

Rev. 0.2

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