Hi, welcome to another HP48 page. What will you find here ? You will find only my personal creations on HP48S/G which focus on high speed serial communication. If you try these programs, please send me your feedback. It will help me to improve them.
The news 16 nov 2001
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FXMIT V1.2
- What is Fxmit ?
Fxmit allows you to transmit data on the serial port of HP48S/G,HP49 calculator with higher rates than 9600 baud.
- What use for Fxmit ?
The first goal of Fxmit is to allow sending data to devices with a serial port faster than 9600 baud. These devices can be : digital camera, MIDI modules (ex: synthesizer)...
Fxmit allows high baud rates but the bit rate is not very higher than the maximal standard one. It is important that you read the "Limitation" part below.
- How does it work ?
Fxmit allow high baud rates by controlling directly the state of the output pin of the serial port.
The available baud range depends on the calculator you have. HP48S/SX have a 2MHz processor which allows lower speed than HP48G/HP49 with a 4MHz one.
HP48S : 12500 - 51700
HP48G : 18000 - 65000 ? (only measured on an emulator)
HP49 : 18000 - 65000 ? (only measured on an emulator)
1 start bit
8 data bits
2 stop bits
no parity
These values are not configurable
- Bit rate limitation
When you use the xmit RPL instruction with the 9600 baud speed to transmit a string you have an effective bit rate of 8*9600/10 bps (with 1 start bit and 1 stop bit). When you use Fxmit, the bit rate is not such optimal. Indeed, Fxmit does not use the UART capabilities to send a byte. It is the saturn processor which prepares data and sends bits one after one. It takes time and little saturn can not manage sending without doing a pause between each byte. For example, with a baud rate of 38400 the bit rate will be about 17000 bps on an HP48S.
- Electrical limitation
HP calculator hardware was designed to transmit data with a maximal baud rate of 9600. So using higher speed leads to electrical problems. Higher is the speed, more the calculator will overwork. For example, if you set a speed of 38400 baud and you send a string of about 200 characters, the calculator may start doing transmission errors after 100 characters. It is why a speed limitation parameter was introduced for allowing the calculator to take energy for next bytes to send.
MIDIPLAY V0.7
With Midiplay you can connect your HP48 (or HP49 but not tested) on your MIDI synthesizer with no need of special hardware and play MIDI files (only MIDI files format 0 are recognized). Before using this software, you need to connect your HP to your synthesizer. You can either use the standard MIDI connector (5 pins DIN, 31250 baud) or use a PC compatible one (8 pins mini DIN, 38400 baud) if your synthesizer has one.
Sylvain Gamot
