Posted on July 21, 2013 at 07:37
Currently im using SPI to send information to configure the internal registers of a ENC28J The minimum SCK allowed is 8 Mhz. Im using the STM32F103RB, which can operate at 78Mhz. For some reason when i try to boost the speed of the SPI to 8 Mhz the signal and data become distorted. Below is a clip from my clock, maybe i made a mistake somewhere. Any help is welcomed.
// 1. Clocking the controller from internal HSI RC (8 MHz)
RCC_HSICmd(ENABLE);
// wait until the HSI is ready
while(RCC_GetFlagStatus(RCC_FLAG_HSIRDY) == RESET);
RCC_SYSCLKConfig(RCC_SYSCLKSource_HSI);
// 2. Enable ext. high frequency OSC
RCC_HSEConfig(RCC_HSE_ON);
// wait until the HSE is ready
while(RCC_GetFlagStatus(RCC_FLAG_HSERDY) == RESET);
// 3. Init PLL
RCC_PLLConfig(RCC_PLLSource_HSE_Div1,RCC_PLLMul_9); // 72MHz
RCC_PLLCmd(ENABLE);
// wait until the PLL is ready
while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);
// 4. Set system clock dividers
/* Select PLL as system clock source */
#ifdef EMB_FLASH
// 5. Init Embedded Flash
// Zero wait state, if 0 < HCLK 24 MHz
// One wait state, if 24 MHz < HCLK 56 MHz
// Two wait states, if 56 MHz < HCLK 72 MHz
// Flash wait state
FLASH_SetLatency(FLASH_Latency_2);
// Half cycle access
FLASH_HalfCycleAccessCmd(FLASH_HalfCycleAccess_Disable);
// Prefetch buffer
FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
#endif // EMB_FLASH
// 5. Clock system from PLL
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
#spi #enc28j60 #stm32f103rb
