Problem in reading/writing to SD card through MPC5554 using high SPI clock speed

Started by sanaas in comp.arch.embedded8 years ago 3 replies

Hi everybody, I have interfaced a 4 GB class 4 Kingston micro SD card with MPC5554 using SPI. I have implemented FAT32 file system driver on...

Hi everybody, I have interfaced a 4 GB class 4 Kingston micro SD card with MPC5554 using SPI. I have implemented FAT32 file system driver on it. Everything(reading/writing files) works fine when I keep SPI clock at 3 MHz after initialization. With 3 MHz clock I am able to write 1 MB of data in a file in 1 min which is pretty low speed!! But when I turn to SPI clock above 3 MHz, the SD card ...


high speed serial synch RS422

Started by ioanc in comp.arch.embedded8 years ago 4 replies

I have an external device that's streaming synchronous data on 2 differential lines, clock and data, with RS422 electrical characteristics. The...

I have an external device that's streaming synchronous data on 2 differential lines, clock and data, with RS422 electrical characteristics. The data is not framed/formatted, words 16 bit long are streamed out. Between words there is a pause, during which the clock is not ticking, of the same length as a word. The clock is at 2.5 MHz (but it doesn't tick between words), so on average I get 1.25 Mbs...


Timer ticks occurring much more faster

Started by ratemonotonic in comp.arch.embedded11 years ago 2 replies

Hi All , I am implementing RTC code on an AVR Atmega2560 I have a 32Khz clock crystal to TSOSC1 which is used by timer2 in async mode. I...

Hi All , I am implementing RTC code on an AVR Atmega2560 I have a 32Khz clock crystal to TSOSC1 which is used by timer2 in async mode. I have configured the clock divide to 8 so the clock to the timer is 32768/8 = 4096. It is a 8bit so a interrupt should be generated every 16hz (4096/256). So on 16 ticks make one second. If I add up second to make 5 minutes and light an LED on this eve...


Silabs c8051f411 I2C,is clock stretching transparent to the programmer?

Started by blisca in comp.arch.embedded11 years ago

Hi to all,thank you for dedicating me a bit of your time. I'm trying to modify a program that i "inherited", it was done for a similar...

Hi to all,thank you for dedicating me a bit of your time. I'm trying to modify a program that i "inherited", it was done for a similar project,where the c8051 acts as a I2C slave; reading the code i saw that in the I2C section done by the SMBus no mention is done to clock stretching. In this case and similar does it means that clock stretching is automatically managed by the SMBus ...


Providing a clock with an MCU

Started by galapogos in comp.arch.embedded12 years ago 11 replies

Hi, I'm trying to communicate with a smart card via iso7816 by emulating the T=0 protocol using a generic MCU's UART interface. One problem...

Hi, I'm trying to communicate with a smart card via iso7816 by emulating the T=0 protocol using a generic MCU's UART interface. One problem I'm having is providing a clock to the smart card(~3.5712MHz) w/o the use of a seperate crystal. Obviously using the GPIO pins would be too slow, and the UART channel doesn't have a SCLK out. It's also impossible to get a divisor for the MCU's clock si...


Real Time Clock Hardware

Started by Tim Wescott in comp.arch.embedded12 years ago 66 replies

I need to put a real-time clock on a board. I haven't needed to know anything about the market for this for years, and I see that I'm way out...

I need to put a real-time clock on a board. I haven't needed to know anything about the market for this for years, and I see that I'm way out of date. I just need basic clock functionality that I can read and set under software control, I don't need any bells or whistles, and I don't care much about the format. What I do care about is something that I can put on the board easily and...


Clock Throttling Utility For Windows?

Started by Slo in comp.arch.embedded12 years ago 1 reply

I've been searching the Internet for a Windows based utility and I'm not finding it: Does anyone know of a utility that does...

I've been searching the Internet for a Windows based utility and I'm not finding it: Does anyone know of a utility that does clock throttling as a function of temperature? As a way of protecting the CPU we need a utility that will slow the system clock when the CPU gets too hot. We have a Pentium M, 855GME, ICH based Processor card with a General Software BIOS. We support SpeedSte...


Silicon Laboratories C8051F060 Slave SPI Issue

Started by Bill Davy in comp.arch.embedded11 years ago

Saw an interesting "feature" on a C8051F060 this week. I do not recall the details, but basically, if I enabled the SPI engine (as a slave)...

Saw an interesting "feature" on a C8051F060 this week. I do not recall the details, but basically, if I enabled the SPI engine (as a slave) with the idle clock in one state, SPIBSY came true immediately and every byte received was shifted by one bit. Worked fine using idle clock in other sense. Luckily I could change the sense of the idle clock (and CLKPOL too, of course). We learn...


Lowest Possible Clock For Blackfin 531

Started by adonis in comp.arch.embedded12 years ago 5 replies

What is the lowest possible clock for BF531 (according to the specifications..)... I checked out the datasheet but it says that it can run upto...

What is the lowest possible clock for BF531 (according to the specifications..)... I checked out the datasheet but it says that it can run upto 400 Mhz... No lower possible value is given... From where to get this value?


Clock and Asynchronous Reset with just one pin

Started by in comp.arch.embedded11 years ago 1 reply

I have a counter chip whose output is decoded. (The 4017 Johnson decade counter). As you clock it, the output pins go high in sequence. It has...

I have a counter chip whose output is decoded. (The 4017 Johnson decade counter). As you clock it, the output pins go high in sequence. It has an asynchronous reset. What I want to do is the following: Loop: * Assert the reset to make sure it starts counting at zero * De-assert the reset * Clock it 8 times goto Loop; Now this would be a trivial exercise if I used two m...


Controlling PCF8583 clock chip with a PIC

Started by John Gruenenfelder in comp.arch.embedded14 years ago 4 replies

I have a board set up with a PIC16F877 microcontroller and on the I2C bus I have a Phillips PCF8583 clock/alarm chip. I am attempting to use...

I have a board set up with a PIC16F877 microcontroller and on the I2C bus I have a Phillips PCF8583 clock/alarm chip. I am attempting to use the alarm function of this chip and thus far am having almost no luck getting it to work. I know the I2C bus is good because I have several other devices on it plus the clock function of this chip is working fine. Specifically, no matter what type ...


68HC11 clocks

Started by Jeff Fox in comp.arch.embedded15 years ago 2 replies

In some literature about the 68HC11 I see a reference to an 8Mhz crystal and a 2MHz eClock. Instructions execute in a given number of clock...

In some literature about the 68HC11 I see a reference to an 8Mhz crystal and a 2MHz eClock. Instructions execute in a given number of clock cycles, but which clock? Best Wishes, Jeff Fox


ImageCraft ICCAVR - Startup ?

Started by Scott Kelley in comp.arch.embedded12 years ago 2 replies

The environment is an ATmega64 with a 32 KHz watch crystal running a real time clock on AVR timer0. The problem is with an occasional...

The environment is an ATmega64 with a 32 KHz watch crystal running a real time clock on AVR timer0. The problem is with an occasional watch dog reset that happens every few days or longer is resetting the AVR processor and wiping out the current real time clock values. The long term fix it to find what is causing the watchdog resets, but saving the real time clock through a watchdog re...


Clock generator for 192KHz USB DAC

Started by Mahen K in comp.arch.embedded9 years ago

I am searching for 192Fs or 128Fs MCLK clock generators for the 192KHz I2S DAC and came across MAX9485 from Maxim and PLL170x from TI....

I am searching for 192Fs or 128Fs MCLK clock generators for the 192KHz I2S DAC and came across MAX9485 from Maxim and PLL170x from TI. The datasheets of these two parts say that they can generate 256Fs or 384Fs for 96KHz sampling rate and do not say anything about support for 192KHz. Can I configure these clock generators for 96KHz @ 256Fs or 96KHz @ 384Fs and use the ouptput as 128Fs or 192F...


what's the startup clock frequency of PIC1703

Started by Johann Klammer in comp.arch.embedded8 months ago 9 replies

I'd like to run from internal osc (XTAL pins as GPIO), but from the configuration bits it looks like it defaults to ext clk. I can't seem to...

I'd like to run from internal osc (XTAL pins as GPIO), but from the configuration bits it looks like it defaults to ext clk. I can't seem to find docs on their two speed startup and Fail-safe clock monitor thingy. Also, will LVP work?


why is freq Internally divided in uPs?

Started by funkymunky in comp.arch.embedded14 years ago 9 replies

Hi, Ive studied the Intel 8085 and the 8051 as part of my curriculum. Im curious to know why in both of these devices, the clock that is...

Hi, Ive studied the Intel 8085 and the 8051 as part of my curriculum. Im curious to know why in both of these devices, the clock that is applied to the device is internally divided by 2? why is half to clock value not given instead? Thanx in anticipation regards Mayank


Processor Clock speed change abd RS232

Started by Anonymous in comp.arch.embedded13 years ago 7 replies

I am looking for a microcontroller with UART that will run at 1Mhz normally and 8Mhz when more power is available. My problem is the receive on...

I am looking for a microcontroller with UART that will run at 1Mhz normally and 8Mhz when more power is available. My problem is the receive on the RS232 when changing the processor clock speed. I think this will cause an upset in any receive characters coming in at the change over. Has any body got any ideas for a low power processor (0.5mA at 1MHz) that can change processor clock speed with...


Variations on XTAL clock frequency

Started by Anonymous in comp.arch.embedded14 years ago 26 replies

Is there any published research/report about how much "uncertainity" and/or variations must be expected on a PC clock frequency ?

Is there any published research/report about how much "uncertainity" and/or variations must be expected on a PC clock frequency ?


LVDS-based LCD Display, Minimum Clock Rates

Started by Prevailing over Technology in comp.arch.embedded8 years ago 1 reply

I have a question regarding the minimum clock rates allowed on LVDS- based LCD display panels. Perhaps someone in the group has some expertise...

I have a question regarding the minimum clock rates allowed on LVDS- based LCD display panels. Perhaps someone in the group has some expertise here. I have HD data coming in at 30 frames per second. I have no place to store a full frame. The HD display panel requires a minimum clock rate of at least 50 MHz (which, according to the display data sheet, equates to about 50 frames per secon...


Code for ATmega88 to receive I2S data (one channel) at 24bit/48kHz

Started by wzab in comp.arch.embedded8 years ago

Hi, I've published (as PUBLIC DOMAIN) on alt.sources my code alllowing to receive and process the 24-bit/48kHz data from the I2S ADC (like...

Hi, I've published (as PUBLIC DOMAIN) on alt.sources my code alllowing to receive and process the 24-bit/48kHz data from the I2S ADC (like CS5343) or left-justified I2S-like ADC (like CS5344). Of course only one channel is received! The code was tested on ATmega88 with 18.432MHz clock The clock to ADC was provided by the pin (PCINT0/CLKO/ICP1) PB0 (of course the clock output was enabled...