Changing clock source in AVR?

Started by Lord Vain in comp.arch.embedded14 years ago 11 replies

I have a Olimex devboard AVR-P28B with a ATMEGA8 on it. I programmed and used it just fine when it was running on the internal RC oscillator. But...

I have a Olimex devboard AVR-P28B with a ATMEGA8 on it. I programmed and used it just fine when it was running on the internal RC oscillator. But I wanted to try to get it working on the 4Mhz crystal so I set the fuse bits and wrote those. Problem is, now it doesn't work anymore and I can't get it to respond and change the fuse bits. How can I program the fuse bits in this situation? I assu...


Depleted CMOS device with integral battery repair

Started by msg in comp.arch.embedded12 years ago 3 replies

Greetings: A recent thread in this N.G. addressed the issue of dead batteries in CMOS Clock/Calendar/RAM devices such as the Dallas DS1287,...

Greetings: A recent thread in this N.G. addressed the issue of dead batteries in CMOS Clock/Calendar/RAM devices such as the Dallas DS1287, DS12887, Twinhead TH6887A, and others; some of these devices are no longer available as new stock and old stock is often also unusable and for many there are no equivalent replacements. Surgery to permit attaching external backup power sources is poss...


[ANN] Atmel invest millions of $ to please Jim Granville

Started by Ulf Samuelsson in comp.arch.embedded15 years ago 15 replies

Read All About it, Read all About it. Atmel releases single clock cycle 8051...

Read All About it, Read all About it. Atmel releases single clock cycle 8051 chips... http://www.atmel.com/dyn/corporate/view_detail.asp?FileName=AT89LP_3_8.html -- Best Regards, Ulf Samuelsson ulf@a-t-m-e-l.com This message is intended to be my own personal view and it may or may not be shared by my employer Atmel Nordic AB


Ethernet daisy chaining

Started by Al Williams in comp.arch.embedded12 years ago 2 replies

I read this in Wikipedia near the end of the RMII docs: http://en.wikipedia.org/wiki/RMII "Since the RMII standard neglected to stipulate that...

I read this in Wikipedia near the end of the RMII docs: http://en.wikipedia.org/wiki/RMII "Since the RMII standard neglected to stipulate that TX_EN should only be sampled on alternate clock cycles, it is not symmetric with CRS_DV and two RMII PHY devices cannot be connected back to back to form a repeater; this is possible, however, with the National DP83848 which supplies the decoded ...


AVR ADC multiplexer

Started by Simon in comp.arch.embedded11 years ago 19 replies

Hi all, I'm trying to sample the AVR's ADC on 3 channels at 8kHz, 8kHz and 16kHz respectively. I've set up a 32kHz interrupt on an 8MHz...

Hi all, I'm trying to sample the AVR's ADC on 3 channels at 8kHz, 8kHz and 16kHz respectively. I've set up a 32kHz interrupt on an 8MHz clock using timer0 (prescale=1, count to 250), and within the timer interrupt handler, I have a state machine which samples ch-1, ch-2, ch-3, ch-2. The code is at http://www.0x0000ff.com/src/main.c if you're interested... To test it, I put a variable re...


Using a 4mhz clock with AVR problems

Started by David Nolen in comp.arch.embedded14 years ago 2 replies

Just getting to know embedded programming with the atmega8. I've had some experience using the PIC chip with MicroCode Studio and...

Just getting to know embedded programming with the atmega8. I've had some experience using the PIC chip with MicroCode Studio and have switched to using the avr-gcc tool chain with the atmega8 chip. I've been spending a good few weeks getting up to speed on transferring my knowledge of the PIC to the avr, looking over the docs and all. I'm using a atmega8 development board from sparkfun w...


FIFO as a Logic Analyzer; Clock synthesizer

Started by Anonymous in comp.arch.embedded14 years ago 2 replies

Hi! I have a big FIFO chip covered by dust, that I'd like to finally use. The most useful application I'm imagining for it is to finally...

Hi! I have a big FIFO chip covered by dust, that I'd like to finally use. The most useful application I'm imagining for it is to finally make myself a logic analyzer. This FIFO (Texas Instruments SN74V3690-6PEU) is a 3.3V device, but has 5V tolerant inputs. "Great!" I thought. What I'm asking you is: should I connect the probes (just a header cable) directly to the FIFO, or should I use ...


Which oscilloscope to go for?

Started by faiyaz in comp.arch.embedded11 years ago 11 replies

Dear all, I am working on a hardware which has AT91SAM7S64, which works on 18.432 MHz main clock. This is the maximum frequency which can be...

Dear all, I am working on a hardware which has AT91SAM7S64, which works on 18.432 MHz main clock. This is the maximum frequency which can be seen on hardware. Now we are planning to buy an analog oscilloscope, we have seen several 30 MHz , 60 MHz and 100 MHz oscilloscopes. The 100 MHZ scope has the least rise time - 3.6 nS, for 60 MHz it is 5-6 nS, 30 MHz has around 11 nS. Can you suggest w...


Achieve baud rate 921600

Started by Soon Heng in comp.arch.embedded15 years ago 4 replies

Hi, How is it possible to achieve fast serial baud rate of 115200,230400,460800,921600? I was trying to communicate with the PC at these...

Hi, How is it possible to achieve fast serial baud rate of 115200,230400,460800,921600? I was trying to communicate with the PC at these rates. Using a 20MHz clock frequency is not possible due to deviation errors? What actually affects the desired baud rate, and how do I achieve this common PC standards?? Thks Heng


ATmega SPI question

Started by habib bouaziz-viallet in comp.arch.embedded15 years ago 14 replies

Hi all, Supposing AVR is a configured as a Master SPI device. Is it possible to discard AVR master SCK output signal and make SCK as an input...

Hi all, Supposing AVR is a configured as a Master SPI device. Is it possible to discard AVR master SCK output signal and make SCK as an input in order to apply external bitstream clock. My app is connecting a Quad voice A/MU law Codec (MSM7705) to an AVR SPI bus. Many thanks


little help with i2c

Started by Attila Csosz in comp.arch.embedded13 years ago 6 replies

Hi, I have a question in the i2c protocol. When the slave or the master sends a data byte the line state will hold the last bit state? For...

Hi, I have a question in the i2c protocol. When the slave or the master sends a data byte the line state will hold the last bit state? For example I send a byte containing "0x01" it means the last bit is "1". The sda line will hold this value ( "1" ) or will be pulled down in the beginning in the next clock cycle? Thanks Attila


SDRAM data garbled due to seperate PCB for SDRAM ???

Started by Mayank Kaushik in comp.arch.embedded15 years ago 19 replies

Hi, Im trying to interface two 128Mbit SDRAMs (MT48LC8M16A2) to the AT91RM9200, but it doesnt seem to be going right. I have a custom...

Hi, Im trying to interface two 128Mbit SDRAMs (MT48LC8M16A2) to the AT91RM9200, but it doesnt seem to be going right. I have a custom board for the AT91, and a seperate board for the SDRAM, the two are connected through an ordinary ribbon cable. The master clock of the uC is running at 60Mhz. To test the integrity of the RAM, im writing data to a series of locations, say from 0x2000_000...


HDLC Synchronous RS232

Started by sunil in comp.arch.embedded14 years ago 8 replies

hi all, iam currently programming MC68360 board processor SCC's to work for Synchronous HDLC and iam taking out RS232 pin outs from the...

hi all, iam currently programming MC68360 board processor SCC's to work for Synchronous HDLC and iam taking out RS232 pin outs from the P2 connector. I have initialized the registers and set jumpers according to the instructions. but iam not getting the Clock signals from the TXCLK lines. can u pls give me some hints what r the things that can go wrong which will lead to this kind of ...


Global Variables Being Overwritten

Started by jgurtner in comp.arch.embedded13 years ago 4 replies

Is there a better way of doing this: LCDWrite("This is a test"); void LCDWrite(char *buffer) { while(*buffer) /* loop until buffer...

Is there a better way of doing this: LCDWrite("This is a test"); void LCDWrite(char *buffer) { while(*buffer) /* loop until buffer is empty */ { PortC = *buffer; /* write data to LCD data port */ LCDEnable(); /* clock the LCD to accept data */ buffer++; /* increment the pointer to the next character */ } } This works fine but it seems that if I...


How to Reset the AT24C01?

Started by Loamlo in comp.arch.embedded14 years ago 3 replies

What is the quickest way to make the data in AT24C01 reset to 0xFF? I write 0xFFto every byte, but that take a long time. Is there any simpler...

What is the quickest way to make the data in AT24C01 reset to 0xFF? I write 0xFFto every byte, but that take a long time. Is there any simpler method? In the datasheet of AT24C01: MEMORY RESET: After an interruption in protocol, power loss or system reset, any 2- wire part can be reset by following these steps: 1. Clock up to 9 cycles. 2. Look for SDA high in each cycle while SCL is high...


FTDI FT245R power requirement

Started by Mark Borgerson in comp.arch.embedded11 years ago 5 replies

I've used the FT245R for USB data upload in a number of data logger designs. I have generally used the logger 3.3V supply to power the chips....

I've used the FT245R for USB data upload in a number of data logger designs. I have generally used the logger 3.3V supply to power the chips. However, I just ran across the following note in the most recent FT245R data sheet: "Notes: 1. The minimum operating voltage VCC must be +4.0V when using the internal clock generator." This not was not present in earlier incarnations of th...


PIC 18 Series - HS+PLL Enabled Clock Mode

Started by John Lucas in comp.arch.embedded15 years ago 2 replies

Hi I am using a PIC18F452 with an external 8MHz crystal. I am trying to enable the HS+PLL Enabled mode, the device programs okay, and...

Hi I am using a PIC18F452 with an external 8MHz crystal. I am trying to enable the HS+PLL Enabled mode, the device programs okay, and when read back, the configuration values are correct, however, in use, the device is still running at 8MHz. I am using MPLAB 6.62 with an ICDII. Can anyone suggest a reason why the PLL may not be working. Thanks John Lucas


programming atmega48

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

comp.arch.embedded programming atmega48 The code below is still not working, but some other code using the external interupt mechanism...

comp.arch.embedded programming atmega48 The code below is still not working, but some other code using the external interupt mechanism strictly to execute a routine is running. The difficulty there was using: sts EIMSK, areg rather than: out EIMSK, areg. Possibly, considering the code below, the clock for the interupts is disabled unless both the specific mask bit and the maste...


Pipelined 6502/z80 with cache and 16x clock multiplier

Started by Brett Davis in comp.arch.embedded9 years ago 101 replies

EETimes had an interesting article asking if 4-bits was dead. http://www.eetimes.com/discussion/other/4211452/Is-4-Bits-Dead- These chips have...

EETimes had an interesting article asking if 4-bits was dead. http://www.eetimes.com/discussion/other/4211452/Is-4-Bits-Dead- These chips have been pad limited for 2 decades, and as such are probably manufactured at fabs that are beyond obsolete. You could take a public CPU design like OpenRISC and replace the instruction decoder, and get an easy ~4x performance jump running 65c802/65c81...


PICmicros instruction counter synchronization

Started by Robert Scott in comp.arch.embedded15 years ago 5 replies

Does anyone know if any of the Microchip PICmicros reset their divide-by-four instruction counter during a hardware reset? I need to drive an...

Does anyone know if any of the Microchip PICmicros reset their divide-by-four instruction counter during a hardware reset? I need to drive an array of PICs from a single clock, and more than that, I need all the PICs to be exactly synchronized with respect to their instruction cycles. I am hoping that releasing them from reset at the same time will accomplish this goal. I am looking primar...