This is my first time using the uM-FPU. I have an EM-406 GPS connected to SERIN of the uM-FPU and have adapted the GPSdemo.bas program from MicroMega to work (some of their original definitions are no longer available, such as SWAP, SIN, ATAN).
The problem is the instability of the PICAXE<->FPU combination. On startup, the FPU chip is identified and the version displayed (most of the time). However, it may or may not display the messages from the GPS - sometimes the code fails waiting for the first message, but it has received and displayed up to 69 messages before everything locks up (must hit reset to download to the PICAXE). The lockup occurs with either sertxd and using the PC to monitor the outputs or with an on-board LCD driven by serout.
The PICAXE 28X2 is on an AXE022 board; the uM-FPU is on a breadboard with the GPS, 3.3 volt regulator, level shifter (GPS serial output is 2.8 volts). The I2C leads are about 2 inches long and are twisted. There is a 100nF cap across the power pins of the uM-FPU.
Power is from a wall-wart with 4.46 volts output.
The code is running in slot 1 of the 28X2.
I would appreciate any ideas.
John
The problem is the instability of the PICAXE<->FPU combination. On startup, the FPU chip is identified and the version displayed (most of the time). However, it may or may not display the messages from the GPS - sometimes the code fails waiting for the first message, but it has received and displayed up to 69 messages before everything locks up (must hit reset to download to the PICAXE). The lockup occurs with either sertxd and using the PC to monitor the outputs or with an on-board LCD driven by serout.
The PICAXE 28X2 is on an AXE022 board; the uM-FPU is on a breadboard with the GPS, 3.3 volt regulator, level shifter (GPS serial output is 2.8 volts). The I2C leads are about 2 inches long and are twisted. There is a 100nF cap across the power pins of the uM-FPU.
Power is from a wall-wart with 4.46 volts output.
The code is running in slot 1 of the 28X2.
I would appreciate any ideas.
John