Uploaded October 2024 | Updated September 2026, 2 weeks ago
*** Fileshare URL is in the description below ***
***See a few clarifications/corrections before the table of contents below***
In this video, I show the new kit from Lee Hart, a "namebadge" (or simply "Badge") based on the vintage 1802 microprocessor. Using a clever 'minimum parts count' circuit, and an equally clever program in firmware (in an EPROM), and NO RAM, it continuously scrolls a 32 character alphanumeric message on its 8-position "starburst" LED display. The message is stored inside the 1802 in its battery-backed internal register bank, and the set of three NiMH cells (the battery) can maintain it for a LONG time. Connecting a USB programming cable (not included) will recharge the battery. The message can be entered and edited using just the three pushbuttons on the Badge. Alternately, any of several inexpensive USB-5V serial adapters, e.g. Sparkfun's 5V FTDI cable (not included) may be used to connect the Badge to a personal computer, and then using any terminal emulator application, the message may be entered/edited using the computer's keyboard and video monitor.
I show the building process of the kit, I demonstrate it operating, and I program messages using both of the two methods. I then give a detailed study of the circuit schematic and theory, and provide some insight into the Badge's firmware.
Finally, I show my design and build of a 3D printed case/holder, as well as my "hack" to allow use of an external toggle switch which is easier to use when entering messages, and I show how I added a green Lexan filter to dramatically improve the clarity of the display.
In the video, I show the URL to my 'fileshare' webpage (serpentwebsite.com/fileshare.htm), where the plans and STL files, and 'build instructions', for the Holder may be downloaded, as well as my chart of all available alphanumeric characters.
***Clarifications/corrections
- The Badge is designed to accommodate an 8k static RAM IC. Although the reserved memory space is indeed 32k for EPROM and 32k for RAM, only address lines A0~A12 (13 bits) are brought to the RAM IC, thus only 8192 bytes (8k) of RAM can be addressed.
- The present program in EPROM is only about 1K bytes, plus about 500 bytes for the character font look-up table, for a total of 1.5K; thus the 8K EPROM is mostly empty.
- The 1802 interrupt 'INT' isn't actually used by the present Badge software. It's there for future expansion of the Badge as a full 1802 computer.
- The pinout adapter for the USB-serial adapter cable is only needed in my case because I chose to use the Sparkfun cable. The Badge comes with a different USB-serial adapter, and its pinout is designed to match that adapter, thus no pinout correction is needed if that other adapter is used.
Timeline table of contents:
00:00 Introduction
03:50 Included parts
08:49 Printed circuit board assembly
16:19 USB adapter
17:04 Initial test
18:27 Programming using the pushbuttons
22:02 Demonstration of programmed message
24:25 Beauty shot
24:43 Programming using a computer via USB
31:57 Schematic & circuit theory
1:23:50 Making a 3D printed Badge Holder
1:52:16 Adding a green filter to the display
*** Fileshare URL is in the description below ***
***See a few clarifications/corrections before the table of contents below***
In this video, I show the new kit from Lee Hart, a "namebadge" (or simply "Badge") based on the vintage 1802 microprocessor. Using a clever 'minimum parts count' circuit, and an equally clever program in firmware (in an EPROM), and NO RAM, it continuously scrolls a 32 character alphanumeric message on its 8-position "starburst" LED display. The message is stored inside the 1802 in its battery-backed internal register bank, and the set of three NiMH cells (the battery) can maintain it for a LONG time. Connecting a USB programming cable (not included) will recharge the battery. The message can be entered and edited using just the three pushbuttons on the Badge. Alternately, any of several inexpensive USB-5V serial adapters, e.g. Sparkfun's 5V FTDI cable (not included) may be used to connect the Badge to a personal computer, and then using any terminal emulator application, the message may be entered/edited using the computer's keyboard and video monitor.
I show the building process of the kit, I demonstrate it operating, and I program messages using both of the two methods. I then give a detailed study of the circuit schematic and theory, and provide some insight into the Badge's firmware.
Finally, I show my design and build of a 3D printed case/holder, as well as my "hack" to allow use of an external toggle switch which is easier to use when entering messages, and I show how I added a green Lexan filter to dramatically improve the clarity of the display.
In the video, I show the URL to my 'fileshare' webpage (serpentwebsite.com/fileshare.htm), where the plans and STL files, and 'build instructions', for the Holder may be downloaded, as well as my chart of all available alphanumeric characters.
***Clarifications/corrections
- The Badge is designed to accommodate an 8k static RAM IC. Although the reserved memory space is indeed 32k for EPROM and 32k for RAM, only address lines A0~A12 (13 bits) are brought to the RAM IC, thus only 8192 bytes (8k) of RAM can be addressed.
- The present program in EPROM is only about 1K bytes, plus about 500 bytes for the character font look-up table, for a total of 1.5K; thus the 8K EPROM is mostly empty.
- The 1802 interrupt 'INT' isn't actually used by the present Badge software. It's there for future expansion of the Badge as a full 1802 computer.
- The pinout adapter for the USB-serial adapter cable is only needed in my case because I chose to use the Sparkfun cable. The Badge comes with a different USB-serial adapter, and its pinout is designed to match that adapter, thus no pinout correction is needed if that other adapter is used.
Timeline table of contents:
00:00 Introduction
03:50 Included parts
08:49 Printed circuit board assembly
16:19 USB adapter
17:04 Initial test
18:27 Programming using the pushbuttons
22:02 Demonstration of programmed message
24:25 Beauty shot
24:43 Programming using a computer via USB
31:57 Schematic & circuit theory
1:23:50 Making a 3D printed Badge Holder
1:52:16 Adding a green filter to the display
