#garfield Logs

Nov 23 2024

07:09 AM polprog: rue_mohr: good call
07:25 AM polprog: ill do that
07:25 AM polprog: i got the electric hob at the supermarket today
07:25 AM polprog: s/hob/stove
09:47 AM Tom_L: https://www.youtube.com/watch?v=rRsZICupppM
12:12 PM rue_mohr: ... stove... not a clothes iron? (their easier to store)
12:12 PM rue_mohr: (but less useful in general)
02:37 PM rue_mohr: hi polprog
02:43 PM polprog: hi rue_mohr
02:43 PM polprog: nah a small stove is easier
02:43 PM rue_mohr: ok, are you going to diy etch the 8051 board?
02:43 PM rue_mohr: its a bit complex...
02:43 PM polprog: noo
02:44 PM rue_mohr: ok
02:44 PM polprog: i ordered that
02:44 PM polprog: i dont etch 2 layers
02:44 PM rue_mohr: so, do you have a render of it with your changes!?
02:44 PM polprog: i could try now that I have the UV photomask, but thats still a lot of holes to drill evenly
02:44 PM polprog: yes, the renders are updated on my guthib
02:44 PM rue_mohr: oh!
02:45 PM rue_mohr: https://github.com/polprog/8051recyclerPCB
02:46 PM polprog: https://polprog.net/rozne1/ircjunk/various/chem/pcb1small.jpg
02:46 PM polprog: this is the electic cooker
02:46 PM rue_mohr: hah, it would be cool if a bunch of people modded it and each added to the silk screen
02:47 PM polprog: https://polprog.net/rozne1/ircjunk/various/chem/pcb2small.jpg developing the photoresist in sodium hydroxide
02:47 PM polprog: https://polprog.net/rozne1/ircjunk/various/chem/pcb3small.jpg etching in ferric chloride
02:47 PM rue_mohr: yea...
02:47 PM polprog: https://polprog.net/rozne1/ircjunk/various/chem/pcb4small.jpg first ready board - overexposed UV mask in my opinion
02:47 PM rue_mohr: the alternate etchants I tried were kinda a fail
02:47 PM polprog: the printer does not cover the foil to well, i have to keep light power low
02:48 PM rue_mohr: did you etch it warm?
02:48 PM polprog: rue_mohr: did you ever try sodium persulfate
02:48 PM polprog: it was about 30 deg C
02:48 PM rue_mohr: yes, I'v used sodium persulphate and ammoniom persulphate
02:48 PM polprog: now that i have the cooker i can heat it up as much as i want
02:48 PM rue_mohr: polprog, yea, about 40c
02:48 PM polprog: i need to figure out the proper potassium iodide concentration to etch copper
02:49 PM rue_mohr: I use a tank and a fishtank heater
02:49 PM rue_mohr: I still have the air-regenerated cupric chloride
02:49 PM rue_mohr: but I dont know how to balance it right
02:49 PM polprog: do you add anything apart from air to regen it?
02:49 PM polprog: muriatic acid?
02:49 PM rue_mohr: yea, it didn't really work out
02:50 PM polprog: i see
02:50 PM rue_mohr: I'm not sure which dimension its wrong in
02:50 PM polprog: i am looking into that chemistry so i wanna try a few various etchants
02:50 PM polprog: did you see my notes about KI:I2 etch?
02:50 PM rue_mohr: I'm not good enough at chemistry to do the tests
02:50 PM rue_mohr: no
02:50 PM polprog: argh
02:50 PM polprog: https://polprog.net/rozne1/ircjunk/various/chem/kietch/iodine-iodide.html
02:52 PM rue_mohr: oh the gold, yea, I did see that
02:55 PM polprog: it is said it also etches copper
02:55 PM polprog: that would be nice to have an etch for both
02:55 PM rue_mohr: ok
02:56 PM rue_mohr: re the pcb, one of the methods for adding extra pins is to take over a GND pin
02:57 PM polprog: adding extra pins for what?
02:57 PM rue_mohr: I'm thinking of the clk pin
02:58 PM rue_mohr: for the cuttable jumper points, I didn't feel like making my own bowtie library
02:58 PM rue_mohr: for normally open and normally closed cuttable pads
02:59 PM polprog: there are some footprints for that
02:59 PM polprog: but a bowtie would be nicer
03:00 PM polprog: hm, well i could just mark which XTAL pin is the amplifier input and then you could solder down to that
03:00 PM polprog: just would need to expose the ground trace there
03:00 PM rue_mohr: see the mask exclusion by the rom for grounding pin (whatever) ?
03:00 PM rue_mohr: for grounding pin 20
03:01 PM polprog: yeah
03:01 PM rue_mohr: there is a hack where a person may want to swap pin 20 and pin 22
03:02 PM rue_mohr: so that allows you to cut the psen to 20 and ground it, and jump psen to 22 after cutting its ground
03:02 PM rue_mohr: thats why the ground connect on 22 is so small
03:02 PM rue_mohr: I think thats needed for an EEPROM
03:03 PM rue_mohr: pin 1, 27, 22, and 20 change around a bit for eeprom/ram/ 64k chips
03:03 PM rue_mohr: technically you can do a 64, 128 256 or 512k chip in there
03:04 PM rue_mohr: I'm going to use 256k, but I wired it up for 512k anyho
03:04 PM rue_mohr: w
03:04 PM rue_mohr: (shower)
03:07 PM polprog: how did you deal with the fact that ROM and RAM are separate address spaces on the '51?
03:07 PM polprog: ROM is /EA and RAM is RD WR
03:08 PM polprog: (sorry, im cleaning up after the etch so i cant look at the sch)
03:20 PM rue_mohr: so
03:20 PM rue_mohr: there is no external ram
03:20 PM rue_mohr: the /PSEN operates the program ROM, and the /rd and /wr lines operate the input and output chips
03:21 PM rue_mohr: if you remove the 2 IO chips you CAN piggyback the ROM less the /OE (/rd) and /WR (/wr) lines
03:21 PM rue_mohr: and have ram
03:22 PM rue_mohr: but you see, then you would have only the 1 8 bit port
03:23 PM rue_mohr: I chose to stay with the internal ram only and have more IO
03:24 PM rue_mohr: the attiny26 is a great chip for IO count, 15 IO
03:24 PM rue_mohr: as the Port 1 is the only bidirectional, adding 8 extra inputs an 8 extra outputs probably works for MOST projects
03:24 PM polprog: right!
03:25 PM polprog: adding external ram would need to make an address decoder to share the ram space with the IO chips
03:25 PM rue_mohr: I'm trying to save my attiny26 to use for ADCs, as they are the cheapest/$ ADC anywhere
03:25 PM rue_mohr: yea, adding IO and ram would become a mess
03:26 PM rue_mohr: I choose to live with the balance, 8 IO and ram, or "16" IO and no ram
03:26 PM rue_mohr: the chips I'v got have 512 bytes ram internal I think
03:26 PM polprog: :)
03:27 PM rue_mohr: these boards are for stupid things and its probably more than enough
03:27 PM rue_mohr: ESP because I have 512k ROM, I can unroll code like crazy
03:34 PM polprog: hah
03:34 PM polprog: -funroll-loop
03:34 PM polprog: -funroll-loops
03:43 PM rue_mohr: :]
03:44 PM rue_mohr: I would like to make a board that can run BASIC, but it would get kinda large and I want to use up some of these on stupid things first
03:44 PM polprog: my 8051 board ran 8051basic
03:44 PM polprog: the arduino shaped one
05:21 PM rue_mohr: yep
05:21 PM rue_mohr: how much ram did you add?
05:31 PM polprog: hmm
05:31 PM polprog: let me check the schem
05:31 PM polprog: there is a single 71256SA
05:32 PM polprog: 14 bits address
05:32 PM polprog: i put A15 to /CS so that the lower half is mapped to the ram and upper can be mapped to IOs
05:32 PM polprog: https://polprog.net/rozne1/ircjunk/8051/8051duino.pdf
05:38 PM rue_mohr: yep, 256k ram
05:39 PM rue_mohr: hahaha FPBC (not FPGA) Field Programmable Basic Controller
05:39 PM rue_mohr: upload its config on startup
05:40 PM polprog: haha
05:40 PM polprog: the 8051 basic can load the code from ROM
05:40 PM polprog: there was some bootstraping pin for that
05:42 PM rue_mohr: yea, but if you upload it on start as a slave controller, you can change its tasks (on the fly?)
05:42 PM rue_mohr: the number of follows on bluesky is insane
05:42 PM rue_mohr: its outnumbering my posts at a rate I dont think I can keep up with
05:42 PM polprog: yeah if you interrupt it and reupload the program
05:43 PM rue_mohr: well, you COULD send realtime basic commands to it too
05:43 PM rue_mohr: OUT 555, 8
05:44 PM rue_mohr: when I was like 8 I came up with a vision of a state machine that was part ROM and part RAM,
05:44 PM rue_mohr: I been trying for ages to understand what I was trying to do
05:44 PM rue_mohr: as I go along its getting more clear, I think
05:46 PM rue_mohr: the line between state machine and CPU is now blurry, the 1 bit computer did a great job breaking the barrier
05:50 PM Tom_L: is that yet another new one?
05:57 PM polprog: bedtime here
05:57 PM polprog: zz
05:57 PM polprog: i hope the 8051 pcbs come next week
05:57 PM rue_mohr: :]
05:57 PM polprog: gn!
05:57 PM rue_mohr: mine wont, (postal strike)