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[avr-chat] 16Mhz or bust
From: |
Mikey Sklar |
Subject: |
[avr-chat] 16Mhz or bust |
Date: |
Mon, 15 Aug 2005 19:37:34 -0500 |
User-agent: |
Mutt/1.5.9i |
I have been working with a ATmega32 through a stk500 under Mac OS/X.
I've had no trouble getting a little test serial program working through
the USART using the 1MHz default internal oscillator. However, I have
had no luck working at running the MCU at higher speeds than 1MHz.
I'm sure someone must have been successful using a AT part at greater
than 1MHz. What am I missing here?
Knobs I've been frobing with:
(note: these settings are known **BAD!**)
- Configuring the ATmega32 for 16MHz
* stk500 - external 16MHz crystal installed
* stk500 - XTAL1 unjumpered
* stk500 - OSCSEL - pins 2,3 jumperred
* Fuse high byte - CKOPT - 10011001 (uisp --wr_fuse_h=0x99)
* Fuse low byte - CKSEL - 11101111 (uisp --wr_fuse_l=0xEF)
* OSCCAL --wr_osc=16000000 (sets to 3686400, perhaps unsigned int issue)
* src code - 16MHz @ 2400bps UBRRL=432 or UBRRL=1B0
I've been using 'uisp' to set the fuse bits. I see at least one issue
with uisp not taking a clock value over 3.6864Mhz. I'm aware of the
usual mistakes:
- Internal oscillator maxes at 8MHz
- Fuse bits are inversed logic (0 is enabled)