| ??? 08/26/05 11:53 Read: times |
#100137 - circuit Responding to: ???'s previous message |
Richard Wiglinski said:
i don't have EPROM. just the EEPROM (the same as in the source list of the circuit above.) I can't see any EEPROM in the circuit in the file you are referring to (page 24). The only memory I can see there is the RAM (btw. do you have a 6264 or a 62256?) Richard Wiglinski said:
the problem with the VCC is the following. i don't have a exact 5V Vcc at home. so i tryed the 3 AAs and it worked perfectly. i could write programs and run them. Did you monitor the voltage on the batteries? The problem might be, they might get drained too quickly. Fresh unloaded zinc-carbon cells have slightly higher voltage than the nominal, around 1.65V; so three of them gave something around 4.95V. However, when loaded by moderate load, they start decreasing their voltage and also they develop higher internal resistance. You should check out the "legal" supply voltage range in the datasheet - for CMOS 80C52s it is 5V+10% (i.e. 5V-5.5V). So below 5V some of the circuits inside the controller might stop working completely correctly and you can get unpredicted behaviour. Richard Wiglinski said:
the only problem was that i couldn't use the PROG commands. as far as i know the different PROG commands save the program to the RAM No, no, not at all. When you write your BASIC program (type in through the terminal), it gets stored immediately into the external RAM. The PROG commands are intended to "burn" it into attached EPROM (but it needs also some additional circuitry). Please check out the BASIC52 manual - if you don't have it, it is floating around on the internet in several forms, including HTML and pdf. There is also no real need storing anything in RAM as it is a volatile memory, so if you disconnect power and reconnect it, it's content is lost (corrupted). Richard Wiglinski said:
the second problem occured yesterday: i figured out that a personal computer has 5V (5.15-5.16V exactly) power so i attached it to the correct lines at the PC but nothing happend. nothing. the circuit doesn't even boot up. but the LED at the circuit was lightning. was the 5.15V to much? I don't think so. But did you measure the 5.15V while your circuit was connected? And then, did you try the "reset" button? PC power supplies have sometimes not too nice startup and the simple RC reset circuit used on the diagram might not reset the microcontroller properly (there is a lot of material on this FOrum, why RC resets are a bad idea). if i type a 10 PRINT 3 or some other line of "programm code" it gives me an error like "invalid line number" (i cann't remember the exact words but it is pretty like this.) Richard Wiglinski said: See above - if you don't have an EPROM and the programming circuitry, nothing gets saved - after reset performs new autobauding.
PS: there is one PROG X command (don't know which exactly) which saves the baud rate. but for how long. if i detach VCC and reattach it it is reseted, right? Jan Waclawek |
| Topic | Author | Date |
| "Software" problem with 8052 basic | 01/01/70 00:00 | |
| Bad RAM | 01/01/70 00:00 | |
| HW? | 01/01/70 00:00 | |
| Oops. | 01/01/70 00:00 | |
| more detailed definition | 01/01/70 00:00 | |
| no nonovolatile memory in 8052 | 01/01/70 00:00 | |
| hey jan | 01/01/70 00:00 | |
| Am I missing something ? | 01/01/70 00:00 | |
| circuit | 01/01/70 00:00 | |
| I do not know anythong about BASIC but w | 01/01/70 00:00 | |
| in fact, there is no EPROM... | 01/01/70 00:00 | |
Burning circuit ? | 01/01/70 00:00 |