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Hi Here's 2 trivial code snippets for configuring and reading the "User Jumpers" on a 56F8357 evaluation board. These are jumpers JG15 and JG16. I configure them as GPIO inputs (open drain). See figure 2-12, section 2.14 of the '357 EVM Hardware User Manual. The alternate functions for these two pins are SPIbus SCLK0 and /SS0. --> It is necessary to configure them for NO PULLUP resistors. <-- I include code for assuring that interrupts are turned off for these pins. You probably don't need to set IENR, IAR or IESR. This code is based on Processor-Expert-style macros, and changes *only* those bits in each cfg registers that you need to change - it leaves the other bits as they were. This isn't efficient code, or clever, but it took me a while to figure out that the external pull-ups (10K according to the EVM Manual) do not (always) overcome the internal pull-ups, so you have to disable the internal pull-ups if you want to read the jumper reliably. Rick Corey void Cfg_ReadGpio_PE4_PE7( void) { // init code for eval board User Jumpers. JG15=PortE_4 JG16=PortE_7 // jumper 1-2 to SET bit. jumper 2-3 for CLEAR bit // first block taken from PE Port D setup, unchanged: no IRQs setReg( *GPIO_E_IENR, getReg( *GPIO_E_IENR ) & ~0x90 ); // GPIO_E_IENR: IEN=0 setReg( *GPIO_E_IAR, getReg( *GPIO_E_IAR ) & ~0x90 ); // GPIO_E_IAR: IA=0 setReg( *GPIO_E_IESR, getReg( *GPIO_E_IESR ) | 0x90 ); // GPIO_E_IESR: IESR=1 ? setReg( *GPIO_E_PPMODE, getReg( *GPIO_E_PPMODE ) | 0x90 ); // GPIO_E_PPMODE: 1=OpenDrain // make pins 4 & 7 of Port E GPIO INPUTS setReg( *GPIO_E_PUR, getReg( *GPIO_E_PUR ) & ~0x90 ); // --> DISABLE the two pull-up resistors on pins 4&7 (PUR=0) <-- setReg( *GPIO_E_DDR, getReg( *GPIO_E_DDR ) & ~0x90 ); // set pins 4&7 to INPUTS (DDR=0) setReg( *GPIO_E_PER, getReg( *GPIO_E_PER ) & ~0x90 ); // pins 4&7 are GPIO (PER=0) } // end Cfg_ReadGpio_PE4_PE7() ushort ReadPortE_Bit( ushort BitNum ) { ushort PortE_DRvalue=0; PortE_DRvalue = *GPIO_E_DR & (1 << BitNum) ; if (PortE_DRvalue) return( TRUE ); else return( FALSE ); /* ushort PortE_DRvalue=0; for (;;) { PortE_DRvalue = *GPIO_E_DR ; PortE_DRvalue &= (1 << BitNum) ; return( PortE_DRvalue ); } */ } Rick Corey Senior Software Engineer DPC Instrument Systems Division |
read User Jumpers, 56F8357 eval. board, code snippets
Started by ●May 13, 2004
