From 66c38cd940714287e4e11729bf688211902b464d Mon Sep 17 00:00:00 2001 From: Dean Camera Date: Sat, 26 Feb 2011 15:57:06 +0000 Subject: Added TWI baud rate prescaler and bit length parameters to the TWI_Init() function (thanks to Thomas Herlinghaus). --- LUFA.pnproj | 2 +- LUFA/Drivers/Peripheral/AVR8/TWI_AVR8.h | 32 +++++++++++++++++++++++++++----- LUFA/ManPages/ChangeLog.txt | 3 ++- Projects/MIDIToneGenerator/makefile | 2 +- Projects/TempDataLogger/TempDataLogger.c | 6 +----- 5 files changed, 32 insertions(+), 13 deletions(-) diff --git a/LUFA.pnproj b/LUFA.pnproj index 4d7c3a983..6e9c49e37 100644 --- a/LUFA.pnproj +++ b/LUFA.pnproj @@ -1 +1 @@ - \ No newline at end of file + \ No newline at end of file diff --git a/LUFA/Drivers/Peripheral/AVR8/TWI_AVR8.h b/LUFA/Drivers/Peripheral/AVR8/TWI_AVR8.h index e03423385..feac8a858 100644 --- a/LUFA/Drivers/Peripheral/AVR8/TWI_AVR8.h +++ b/LUFA/Drivers/Peripheral/AVR8/TWI_AVR8.h @@ -53,7 +53,7 @@ * Low Level API Example: * \code * // Initialise the TWI driver before first use - * TWI_Init(); + * TWI_Init(TWI_BIT_PRESCALE_1, 10); * * // Start a write session to device at device address 0xA0, internal address 0xDC with a 10ms timeout * if (TWI_StartTransmission(0xA0 | TWI_ADDRESS_WRITE, 10)) @@ -92,7 +92,7 @@ * High Level API Example: * \code * // Initialise the TWI driver before first use - * TWI_Init(); + * TWI_Init(TWI_BIT_PRESCALE_1, 10); * * // Start a write session to device at device address 0xA0, internal address 0xDC with a 10ms timeout * uint8_t InternalWriteAddress = 0xDC; @@ -155,6 +155,18 @@ */ #define TWI_DEVICE_ADDRESS_MASK 0xFE + /** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 1. */ + #define TWI_BIT_PRESCALE_1 ((0 << TWPS1) | (0 << TWPS0)) + + /** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 4. */ + #define TWI_BIT_PRESCALE_4 ((0 << TWPS1) | (1 << TWPS0)) + + /** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 16. */ + #define TWI_BIT_PRESCALE_16 ((1 << TWPS1) | (0 << TWPS0)) + + /** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 64. */ + #define TWI_BIT_PRESCALE_64 ((1 << TWPS1) | (1 << TWPS0)) + /* Enums: */ /** Enum for the possible return codes of the TWI transfer start routine and other dependant TWI functions. */ enum TWI_ErrorCodes_t @@ -170,11 +182,21 @@ /* Inline Functions: */ /** Initialises the TWI hardware into master mode, ready for data transmission and reception. This must be * before any other TWI operations. + * + * The generated SCL frequency will be according to the formula 
F_CPU / (16 + 2 * BitLength + 4 ^ Prescale)
. + * + * \note The value of the \c BitLength parameter should not be set below 10 or invalid bus conditions may + * occur, as indicated in the AVR8 microcontroller datasheet. + * + * \param[in] Prescale Prescaler to use when determining the bus frequency, a \c TWI_BIT_PRESCALE_* value. + * \param[in] BitLength Length of the bits sent on the bus. */ - static inline void TWI_Init(void) ATTR_ALWAYS_INLINE; - static inline void TWI_Init(void) + static inline void TWI_Init(const uint8_t Prescale, const uint8_t BitLength) ATTR_ALWAYS_INLINE; + static inline void TWI_Init(const uint8_t Prescale, const uint8_t BitLength) { - TWCR |= (1 << TWEN); + TWCR |= (1 << TWEN); + TWSR = Prescale; + TWBR = BitLength; } /** Turns off the TWI driver hardware. If this is called, any further TWI operations will require a call to diff --git a/LUFA/ManPages/ChangeLog.txt b/LUFA/ManPages/ChangeLog.txt index 04ce841d3..3159f2c3d 100644 --- a/LUFA/ManPages/ChangeLog.txt +++ b/LUFA/ManPages/ChangeLog.txt @@ -22,7 +22,8 @@ * - Added new MAX() and MIN() convenience macros * - Added new Serial_SendData() function to the Serial driver * - Added board driver support for the Sparkfun ATMEGA8U2 breakout board - * - Started internal restructuring for eventual multiple architecture ports + * - Added TWI baud rate prescaler and bit length parameters to the TWI_Init() function (thanks to Thomas Herlinghaus) + * - Internal restructuring for eventual multiple architecture ports * - Added start of an AVR32 UC3B architecture port (currently incomplete/experimental) * - Library Applications: * - Added ability to write protect Mass Storage disk write operations from the host OS diff --git a/Projects/MIDIToneGenerator/makefile b/Projects/MIDIToneGenerator/makefile index 6e1a2a32b..4ae786221 100644 --- a/Projects/MIDIToneGenerator/makefile +++ b/Projects/MIDIToneGenerator/makefile @@ -116,7 +116,7 @@ OBJDIR = . # Path to the LUFA library -LUFA_PATH = ../../ +LUFA_PATH = ../.. # LUFA library compile-time options and predefined tokens diff --git a/Projects/TempDataLogger/TempDataLogger.c b/Projects/TempDataLogger/TempDataLogger.c index ecea2fb1a..cd511f4f7 100644 --- a/Projects/TempDataLogger/TempDataLogger.c +++ b/Projects/TempDataLogger/TempDataLogger.c @@ -151,10 +151,6 @@ int main(void) LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY); sei(); - /* Discard the first sample from the temperature sensor, as it is generally incorrect */ - volatile uint8_t Dummy = Temperature_GetTemperature(); - (void)Dummy; - for (;;) { MS_Device_USBTask(&Disk_MS_Interface); @@ -204,7 +200,7 @@ void SetupHardware(void) Temperature_Init(); Dataflash_Init(); USB_Init(); - TWI_Init(); + TWI_Init(TWI_BIT_PRESCALE_4, (F_CPU / 4 / 50000) / 2); /* 500ms logging interval timer configuration */ OCR1A = (((F_CPU / 1024) / 2) - 1); -- cgit v1.2.3